task(settings): Optimize sentry bundle and add webpack analyzer

[dschom]

Because

• We are optimizing our bundle size

This pull request

• Adds sentry plugin to tree sentry module from webpack

Issue that this pull request solves

Closes: FXA-9647

Checklist

Put an x in the boxes that apply

• My commit is GPG signed.
• If applicable, I have modified or added tests which pass locally.
• I have added necessary documentation (if appropriate).
• I have verified that my changes render correctly in RTL (if appropriate).

Screenshots (Optional)

Before:

After:

Other information (Optional)

To run this yourself, run BUILD_TARGETS=prod yarn workspace fxa-settings build-react-prod.

Looking at the webpack analyzer results are interesting too. You'll find them in packages/fxa-settings/build/prod

Also if you set the SENTRY_SOURCE_MAP_AUTH_TOKEN this plugin will supposedly upload better source maps to sentry and potentially give us better errors. TBD if this actually works. A token can be created here: https://sentry.io/orgredirect/organizations/mozilla/settings/auth-tokens/

[chenba]

Dan is on PTO so I'm going to merge this.