Add support for `x-tagGroups`

[robert-pitt-foodhub]

Add Support for x-tagGroups

See: https://redocly.com/docs-legacy/api-reference-docs/specification-extensions/x-tag-groups

• Added sidebar support for x-tagGroups
• Updated react and web component stories
• Added unit test case to ensure tree layout is correct when x-tagGroups is defined.

Screenshot:

• [x] Read CONTRIBUTING.md

Other Available PR Templates:

• Release: https://github.com/stoplightio/elements/compare?template=release.md
  • [x] Read the release section of CONTRIBUTING.md

Closes: #1390

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[robert-pitt-foodhub]

Another example using my own api schema...

[weyert]

Don't expect it being merged any time soon: https://github.com/stoplightio/elements/pull/2603

[weyert]

Any chance we can approve this PR? @robert-pitt-foodhub maybe we should start our own fork ;)