Deprecate w3c-common profile and simplify other profiles

[sidvishnoi]

• Freeze w3c-common (https://github.com/w3c/respec/pull/2838)
• Add a migration guide (https://github.com/w3c/respec/wiki/respec-w3c-common-migration-guide)
• Blocker - Extensions: https://github.com/w3c/respec/issues/1976
• Add deprecation warning to w3c-common (https://github.com/w3c/respec/pull/3109)
• Remove code due to legacy support (https://github.com/w3c/respec/pull/2839)
• Remove jQuery entirely (https://github.com/w3c/respec/pull/3023)
• Fix highlightjs dynamic language loading - uses accessing worker with require
• Fix tools/respecDocWriter.js - uses exporter with require (https://github.com/w3c/respec/pull/3403)
• Remove require support - do not expose anymore - BREAKING CHANGE

[sidvishnoi]

Before we start deprecation warning, we should add a migration guide.
As we plan to remove require(["some-respec-internal-thing"]), we should figure out a strategy for extensions also (See https://github.com/w3c/respec/issues/1976), otherwise migration is like "check back later".
Edit: added in checklist above.

[JohnRiv]

I'm not sure if https://github.com/w3c/respec/wiki/respec-w3c-common-migration-guide was ever created, but that page does not exist anymore

[sidvishnoi]

Thanks for reporting! It's up again.

Damn bots deleted the page.

[carmacleod]

The migration guide is gone again, fyi.

[sidvishnoi]

Thanks for reporting @carmacleod. Added it back again, and restricted wiki edit access for some time.