Improve UX for initial loading on site frontend

[jeffpaul]

Is your enhancement related to a problem? Please describe.
From @dkotter in #6:

On the FE, right now it renders out the audio players and then those get replaced with the WebAmp player. Thinking some basic styling here where those players get hidden and maybe some sort of placeholder container, so once the player loads in it's not shifting the page contents around

Describe the solution you'd like
Review the work in #6, the current state of the develop branch, and what approach should (if any) be taken to resolve this issue.

Designs

Describe alternatives you've considered

Additional context

[jeffpaul]

Could the plugin ship with the base skin images and render those initially until the player and correct skin and audio file(s) load in?

[dkotter]

I've pushed some changes that help with the front-end a bit. We change the individual audio players from having src attributes to data-src attributes. This prevents the audio files from loading unnecessarily which helps with load times. We then hide those audio players so they never show.

In my testing, the WebAmp player loads in fairly quickly, so while I still think it would be nice to have some sort of placeholder or loading indicator, things are better now

[jeffpaul]

@fabiankaegy any tweaks you might recommend on initial UX here?