cli/run: Require either --executable or --program

[guihkx]

Description

This prevents a crash when bottles-cli run is invoked without an --executable or --program.

Fixes #3559

Type of change

• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to not work as expected)
• This change requires a documentation update

How Has This Been Tested?

• Without the fix:

$ flatpak run --command=bottles-cli com.usebottles.bottles run -b Default
05:35:27 (INFO) Forcing offline mode 
Traceback (most recent call last):
  File "/app/bin/bottles-cli", line 764, in <module>
    cli = CLI()
          ^^^^^
  File "/app/bin/bottles-cli", line 236, in __init__
    self.__process_args()
  File "/app/bin/bottles-cli", line 285, in __process_args
    self.run_program()
  File "/app/bin/bottles-cli", line 687, in run_program
    _executable = _executable.replace("file://", "")
                  ^^^^^^^^^^^^^^^^^^^
AttributeError: 'NoneType' object has no attribute 'replace'

• With the fix:

$ flatpak run --command=bottles-cli com.usebottles.bottles run -b Default
05:41:20 (INFO) Forcing offline mode 
Please specify either --executable or --program