Add --retry-open flag

esp-idf-monitor frequently fails when trying to open the serial port of a device
which deep-sleeps often.

e.g.:

```
--- esp-idf-monitor 1.4.0 on /dev/cu.usbmodem6101 115200 ---
--- Quit: Ctrl+] | Menu: Ctrl+T | Help: Ctrl+T followed by Ctrl+H ---
[Errno 2] could not open port /dev/cu.usbmodem6101: [Errno 2] No such file or directory: '/dev/cu.usbmodem6101'
Connection to /dev/cu.usbmodem6101 failed. Available ports:
/dev/cu.usbmodemF554393F21402
/dev/cu.AspergitosII
/dev/cu.Bluetooth-Incoming-Port
```

esp-idf-monitor currently already waits for the serial port _if_ it was
opened successfully. This, however, doesn't help when opening the device for the first time.

This PR adds a new flag `--retry-open` which retries opening the port indefinitely until the
device shows up:

```
--- esp-idf-monitor 1.4.0 on /dev/cu.usbmodem6101 115200 ---
--- Quit: Ctrl+] | Menu: Ctrl+T | Help: Ctrl+T followed by Ctrl+H ---
[Errno 2] could not open port /dev/cu.usbmodem6101: [Errno 2] No such file or directory: '/dev/cu.usbmodem6101'
Retrying to open port ......
ESP-ROM:esp32s3-20210327

```

esp_idf_monitor/base/argument_parser.py

@@ -139,4 +139,10 @@ def get_parser():  # type: () -> argparse.ArgumentParser
         default=False,
         action='store_true')
 
+    parser.add_argument(
+        '--retry-open',
+        help='Retry opening the port device for the first time if it does not exist',
+        default=False,
+        action='store_true')
+
     return parser

esp_idf_monitor/base/serial_reader.py

@@ -25,12 +25,13 @@ class SerialReader(Reader):
     event queue, until stopped.
     """
 
-    def __init__(self, serial_instance, event_queue, reset, target):
-        #  type: (serial.Serial, queue.Queue, bool, str) -> None
+    def __init__(self, serial_instance, event_queue, reset, retry_open, target):
+        #  type: (serial.Serial, queue.Queue, bool, bool, str) -> None
         super(SerialReader, self).__init__()
         self.baud = serial_instance.baudrate
         self.serial = serial_instance
         self.event_queue = event_queue
+        self.retry_open = retry_open
         self.gdb_exit = False
         self.reset = reset
         self.reset_strategy = Reset(serial_instance, target)
@@ -43,16 +44,34 @@ def run(self):
         #  type: () -> None
         if not self.serial.is_open:
             self.serial.baudrate = self.baud
-            try:
-                # We can come to this thread at startup or from external application line GDB.
-                # If we come from GDB we would like to continue to run without reset.
-                self.open_serial(reset=not self.gdb_exit and self.reset)
-            except serial.SerialException as e:
-                print(e)
-                # if connection to port fails suggest other available ports
-                port_list = '\n'.join([p.device for p in list_ports.comports()])
-                yellow_print(f'Connection to {self.serial.portstr} failed. Available ports:\n{port_list}')
-                return
+            printed_failure = False
+            retry_attempts = 0
+            while True:
+                try:
+                    # We can come to this thread at startup or from external application line GDB.
+                    # If we come from GDB we would like to continue to run without reset.
+                    self.open_serial(reset=not self.gdb_exit and self.reset)
+                    if retry_attempts > 0:
+                        # break the retrying line
+                        print("")
+                    break
+                except serial.SerialException as e:
+                    if retry_attempts == 0:
+                        print(e)
+                        if self.retry_open:
+                            # only print this once
+                            yellow_print("Retrying to open port ", newline='')
+                    if self.retry_open:
+                        if retry_attempts % 9 == 0:
+                            # print a dot every second
+                            yellow_print(".", newline='')
+                        time.sleep(0.1)
+                        retry_attempts += 1
+                        continue
+                    # if connection to port fails suggest other available ports
+                    port_list = '\n'.join([p.device for p in list_ports.comports()])
+                    yellow_print(f'Connection to {self.serial.portstr} failed. Available ports:\n{port_list}')
+                    return
             self.gdb_exit = False
         try:
             while self.alive:

esp_idf_monitor/idf_monitor.py

@@ -90,6 +90,7 @@ def __init__(
         make='make',  # type: str
         encrypted=False,  # type: bool
         reset=DEFAULT_TARGET_RESET,  # type: bool
+        retry_open=False, # type: bool
         toolchain_prefix=DEFAULT_TOOLCHAIN_PREFIX,  # type: str
         eol='CRLF',  # type: str
         decode_coredumps=COREDUMP_DECODE_INFO,  # type: str
@@ -128,7 +129,7 @@ def __init__(
             # testing hook: when running tests, input from console is ignored
             socket_test_mode = os.environ.get('ESP_IDF_MONITOR_TEST') == '1'
             self.serial = serial_instance
-            self.serial_reader = SerialReader(self.serial, self.event_queue, reset, target)  # type: Reader
+            self.serial_reader = SerialReader(self.serial, self.event_queue, reset, retry_open, target)  # type: Reader
 
             self.gdb_helper = GDBHelper(toolchain_prefix, websocket_client, self.elf_file, self.serial.port,
                                         self.serial.baudrate) if self.elf_exists else None
@@ -408,6 +409,7 @@ def main() -> None:
                       args.make,
                       args.encrypted,
                       not args.no_reset,
+                      args.retry_open,
                       args.toolchain_prefix,
                       args.eol,
                       args.decode_coredumps,