Removes Webpacker.

[scherztc]

This should transition us off of webpacker to jsbundle according to the transition guide : https://github.com/rails/jsbundling-rails/blob/main/docs/switch_from_webpacker.md

This also fixes the cap qa deploy problems.

Fixes #212
Fixes #214

[Janell-Huyck]

@scherztc That's fantastic! I went ahead and test-deployed it on qa, and it deploys fine. It runs locally fine. I'd feel more comfortable if @crowesn or @hortongn took a peek at the PR before we merge it up, but it looks good to me. Thank you!!

[hortongn]

@scherztc Nice fix! I don't have any requested changes, but two questions:

1. This PR includes changes to scripts/start_qp.sh for the puma service. Is that intended to be merged or was that a temporary change? Is there another issue or PR already handling the service changes?

2. Do we expect to need this fix in our other applications? Was it the updated webpacker causing the problem? I'm just seeing if we can anticipate when this will show up in our other apps.

[crowesn]

@hortongn For your first question, after a quick review, I realized we didn't have an issue that touched directly on the puma daemon deprecation, I created one here: #214

[crowesn]

Looks good, merging.