Add GitHub Actions workflow for WebOS IPTV Simple PVR addon build

[alpgul]

Added Workflow:

• Added a new workflow to support building addons for webOS.
• Implemented cache management to optimize performance.
  • Cache covers 2GB of storage space.
• Improved application runtime:
  • Without cache: ~30 minutes.
  • With cache: ~1.5 minutes.

[phunkyfish]

Really WebOS should be build as part of Jenkins and not as a separate job.

[alpgul]

The Jenkins artifact outputs can also be added to the release notes or asserts so that users can try them out.