lua-plugins: Code cleanup and bug fixes

 * Reduce the number of helper functions
 * Better use of the api map variable
 * Map all the supported keys
 * Check for skip equal to zero on the browser callback
1 job for radio_browser_plugin in 4 minutes and 16 seconds (queued for 4 seconds)
latest
Status Job ID Name Coverage
  Test
passed #114767
build_stable

00:04:16