Simple access to logcat entries while emulator is running

[michaelkaye]

This does not add a new feature, as we can do this work in the script tag, but it would reduce boilerplate in github workflow configurations.

I've seen in a number of examples things like this:

     - name: run tests
        uses: reactivecircus/android-emulator-runner@v2
        with:
          api-level: 29
          script: | 
            adb logcat -c
            adb logcat > temporary-file & /or/ adb logcat &
            ./gradlew <actual script here>

And then the temporary file is printed or pushed into a github action artifact, or printed inline the build.

this feels like this could be better expressed as config like:

     - name: run tests
        uses: reactivecircus/android-emulator-runner@v2
        with:
          api-level: 29
          logcat-to: ./logs
          script: ./gradlew connectedCheck

Such that if configured, the action would:

• launch the emulator
• clear the logcat ring buffer with -c
• keep all logcat logs from the emulator in a local file, by running adb logcat in the background, or by polling or by doing Something Useful to make sure the logs go to the right place.
• move that completed file into the named location after the script completes

[mrk-han]

If running with orchestrator may need to get all the logs from outputs and put together.

I could see this being somewhat useful, but devil's advocate says that it may add unnecessary bloat to the action.

I'll label this as help-wanted though