[Linux] Add test logic to verify the subscription state in the Linux tv-casting-app.

[shaoltan-amazon]

Continuing on from #32787, #32918, #33300, and #33343.

There is no CI check to verify that the Linux tv-casting-app is still correctly subscribing to the MediaPlayback Cluster and CurrentState Attribute whenever a PR is created. Therefore, this issue will add the logic needed to the run_tv_casting_test.py file to check the subscription state of the tv-casting-app by finding a ReportDataMessage block with the relevant cluster and attribute values.

Essentially, we will be parsing the output of the Linux tv-casting-app for the relevant ReportDataMessage block and confirm that the tv-casting-app is subscribed to the MediaPlayback cluster and the CurrentState (playback state) attribute. If the relevant ReportDataMessage block is not found within a given timeout, then we will log the error, dump the logs to the console, and exit on error.