upgrade gulp-autoprefixer

[brad-decker]

Explanation

On every new process we are getting spammed with a message about caniuse browserlists being outdated. This PR upgrades the dependency that depends on that package, and removes the resolution for caniuse-browserslist which was pinned to an older version. In addition the autoprefixer output now caught two issues with us using 'end' and 'start' intsead of 'flex-end' and 'flex-start'. I also added a .browserslistrc file with our target browsers in it which autoprefixer will pickup on and use.

Screenshots/Screencaps

Before

After

Example of *helpful errors*

After cleanup

Manual Testing Steps

1. pull this branch
2. yarn setup
3. yarn start, notice no spamming of the caniuse-lite is outdated message
4. profit

Pre-merge author checklist

• I've clearly explained:
  • What problem this PR is solving
  • How this problem was solved
  • [x/ How reviewers can test my changes
• Sufficient automated test coverage has been added

Pre-merge reviewer checklist

• Manual testing (e.g. pull and build branch, run in browser, test code being changed)
• PR is linked to the appropriate GitHub issue
• IF this PR fixes a bug in the release milestone, add this PR to the release milestone

[mcmire]

Good change — makes sense to me!

[metamaskbot]

Builds ready [bc63617]

• builds: chrome, firefox
• builds (beta): chrome, firefox
• builds (flask): chrome, firefox
• build viz: Build System
• mv3: Background Module Init Stats
• mv3: UI Init Stats
• mv3: Module Load Stats
• mv3: Bundle Size Stats
• mv2: E2e Actions Stats
• code coverage: Report
• storybook: Storybook
• typescript migration: Dashboard
• all artifacts
• bundle viz:

  • background: 0, 1, 2, 3, 4
  • common: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9
  • content-script: 0
  • contentscript: contentscript
  • disable-console: disable-console
  • inpage: inpage
  • policy-load: policy-load
  • sentry-install: sentry-install
  • ui: 0, 1, 2, 3, 4, 5, 6, 7, 8, 9

Page Load Metrics (2314 ± 151 ms)

Platform	Page	Metric	Min (ms)	Max (ms)	Average (ms)	StandardDeviation (ms)	MarginOfError (ms)
Chrome	Home	firstPaint	91	197	114	25	12
		domContentLoaded	1791	2933	2281	302	145
		load	1854	3032	2314	315	151
		domInteractive	1791	2933	2281	302	145

Bundle size diffs [🚀 Bundle size reduced!]

• background: 0 bytes
• ui: 3275 bytes
• common: -41 bytes

highlights:

storybook

• ui/pages/confirm-add-suggested-token/confirm-add-suggested-token.stories.js
• ui/pages/confirm-approve/confirm-approve.stories.js
• ui/pages/confirm-import-token/confirm-import-token.stories.js
• ui/pages/confirm-token-transaction-base/confirm-token-transaction-base.stories.js