Bm webpack5 config fixes

[Bianca-Morris]

Changelog:

• Remove terser-webpack-plugin dev-dependency, since this is now included in Webpack 5 by default
• No longer bundle source maps in production builds (just adds to the bundle size and makes site load slower)
  • Note: this may make debugging issues on live environments more difficult, but since less work will be happening on CGAP into the future, shouldn't be as much of an issue as when it was in active development. May not implement this change on SMaHT until that portal is in the same state.
  • Also, no longer using "eval" as devtool (seems we were never supposed to do that -- honestly not sure how this was working before)
• Re-add build-quick script, since it will now serve a unique purpose, given default builds are running a little long these days
• Added some comments we can use to easily profile while debugging Webpack
• Resolve NODE_ENV "Conflicting values for 'process.env.NODE_ENV'" warning

Notes:

• Need to look into why the builds are taking so much longer than they used to (~3 min or so); more profiling and troubleshooting required
• Bundle sizes are still larger than we'd like... another thing to look into

Related PRs:

• Babel updates PR should probably be merged before this