Upgrade to Storybook 6.4

[robinmetral]

Purpose

Upgrades to Storybook 6.4.

Approach and changes

• Ran the sb upgrade util (updates all sb dependencies)
• Added minor tweaks to main.js
  • I had to add the new 6.4 emotionAlias: false; config, which is supposed to make sb compatible with emotion 11, but I still had to keep the old workaround in place (webpack aliases)
  • I had to add an extra webpack alias for @emotion/styled/base (legacy emotion 10) to @emotion/styled (emotion 11)
• Addressed a deprecation warning for the sb CLI -s flag, which we were using to point to our storybook static dir
• Fixed linting after prettier was bumped under the hood (in sb, the dependency changed from ~2.2.1 to ^2.2.1, resulting in an effective bump from 2.2.1 to 2.5.1)
• Fixed the warnings we were getting about the babel loose mode when starting storybook, by declaring three underlying babel plugins in all babel configs with the loose option set to true. We were already doing this for a single one of these plugins

Definition of done

• Development completed
• Reviewers assigned
• Unit and integration tests
• Meets minimum browser support
• Meets accessibility requirements

[changeset-bot]

⚠️ No Changeset found

Latest commit: d225dff

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[codecov]

Codecov Report

Merging #1303 (d225dff) into main (044a7bc) will increase coverage by 0.03%.
The diff coverage is 84.41%.

@@            Coverage Diff             @@
##             main    #1303      +/-   ##
==========================================
+ Coverage   92.30%   92.34%   +0.03%     
==========================================
  Files         186      186              
  Lines        3667     3671       +4     
  Branches     1148     1147       -1     
==========================================
+ Hits         3385     3390       +5     
+ Misses        265      264       -1     
  Partials       17       17              

Impacted Files	Coverage Δ
packages/circuit-ui/util/shared-prop-types.js	42.85% <11.11%> (+2.85%)	⬆️
packages/circuit-ui/components/Popover/Popover.tsx	96.07% <75.00%> (+0.03%)	⬆️
packages/circuit-ui/components/Table/utils.ts	93.75% <90.90%> (+0.20%)	⬆️
...omponents/CalendarTagTwoStep/CalendarTagTwoStep.js	61.22% <100.00%> (ø)
...it-ui/components/Card/components/Header/Header.tsx	92.30% <100.00%> (ø)
packages/circuit-ui/components/Col/utils.js	92.50% <100.00%> (+0.19%)	⬆️
.../components/ComponentsContext/ComponentsContext.ts	100.00% <100.00%> (ø)
...es/circuit-ui/components/IconButton/IconButton.tsx	89.47% <100.00%> (ø)
...cuit-ui/components/InlineMessage/InlineMessage.tsx	94.73% <100.00%> (-0.27%)	⬇️
...ircuit-ui/components/ModalContext/ModalContext.tsx	91.48% <100.00%> (+0.18%)	⬆️
... and 7 more

[connor-baer]

Whoop whoop, big kudos for getting this to work! 🚀