Introduce GitHub actions

[jkoan]

This is the first take on Github Actions. The goal is to migrate all our builds to it as CircleCI has issues for a long time.
The most prominent is that when opening a PR no Builds are done, or those are not reported back to Github Checks.
On the other Hand Github Actions is obviously perfectly integrated and therefor has additional advantages, like allowing to start workfows, suggestins and many more.
Some of those will be integrated into this PR. The first and most notable one will be that the Build Sanity Check will now post Formatting errors back to the Contributor (within the PR) so that they can be applied with a single click.

[jkoan]

@mvglasow @jandegr could you make sense of this Lint Error? https://github.com/navit-gps/navit/pull/1162/checks?check_run_id=3802624465 i looked it up, but its apparently a error in the Linter with some Versions. But i don't see any config where we directly define the Linter Version used.

[mvglasow]

Error:   /home/runner/work/navit/navit/navit/android/src/org/navitproject/navit/NavitTraff.java:360: Error: Value must be ≥ 0 [Range]
                  builder.append(cursor.getString(cursor.getColumnIndex(COLUMN_DATA))).append("\n");
                                                  ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

Lint apparently complains because it expects to see a non-negative argument for cursor.getString(). Instead of a numeric argument, we are using the return value of cursor.getColumnIndex() with a String constant argument. In practice, this works well as long as the cursor has a column named data (which is the value of COLUMN_DATA).

This might not be the most elegant way of coding it. A way to get rid of the lint warning would be something like:

int columnDataIndex = cursor.getColumnIndex(COLUMN_DATA);
if (columnDataIndex < 0) {
    // some error handling here
} else {
    builder.append(cursor.getString(columnDataIndex)).append("\n");
}

If someone wants to take a stab a this, feel free – I can’t currently dedicate much time to Navit (unfortunately).