meterWidget: fix sound playing indefinitely on reload and enhancement to fullscreen mode

[ksraj123]

This PR does the following

• fixes sound playing indefinitely bug when reloaded while playing
• enhances fullscreen mode for this widget
• adds jsDoc style documentation
• fixes linting issues
• prettifies code

Related Issues #2767, #2630, #2609

Bug Details

When the sound is playing and the widget is reloaded with new settings then the widget reloads but the sound does not stop playing and it plays indefinitely. Even closing the widget does not stop it. The ideal behaviour should be that the sound should stop playing when the widget is reloaded.

Please keep audio on while playing the video below to notice the bug.

meter_bug.mov

Enhancement Details

Fullscreen mode does nothing, the extra space in fullscreen mode is not utilised in a meaningful way.

After Changes

• Sound playing indefinitely on reload while playing bug fixed. Upon reloading the sound stops if playing.

Please keep audio on while playing the video below to notice the changes.

meter_bug_after.mov

• Full screen mode enhanced

[meganindya]

Looks good. However, something seems to be off with the save action. The action block doesn't get generated on my end. Pls verify.

[ksraj123]

@meganindya save seems to be working fine. I guess the action blocks are not meant to be generated but are to specify some action to be performed (similar functionality in master too).
Here's a short walkthrough of my testing

meter_save_working_fine.mov

[meganindya]

Oh! You're right. Absolutely rolled off my mind :D