Replace webpacker with Vite

[eliotjordan]

Closes #1377

• We had to ensure there were no lux tags around elements with javascript events bound to them.
• Migrated local javascript to be served by Vite. Sprockets is still needed to serve upstream javascript.

[tpendragon]

This works well for me.

Are we expecting any problems if Spotlight chooses a different packaging solution, and are comfortable switching to it if so?

[hackartisan]

We should add something to the readme about running bin/vite dev

[hackartisan]

I updated the development documentation.

Re: spotlight decisions, I believe spotlight will have to make their javascript packages available via npm in order to participate in the current ecosystem. That said, if it turns out they do something that's incompatible with vite, we have discussed the possibility that we may need to move to a different tool and feel comfortable with that possibility.

Changes addessed