[plan] linter 2.0

[pq]

Now that #3848 has landed, we can set our sights on a more interesting release that lines up with some of the bigger changes we want to make for Dart 3.0.

Top of mind for me are removals and deprecations

• remove deprecated lints in 3.0 #3880
• proposal: deprecate (and remove?) lints for 3.0 #3879 (which probably implies review experimental lints for 3.0 #3881)

but assuming the analyzer bits are done, this would be a good time to prioritize new language feature support, time permitting.

A key piece to support removals is the idea of a more rich "status" object and will have to happen in the analyzer (#3896) , so I'll be putting energy into that over the next week.

As always, feedback most welcome!

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/fyi @bwilkerson @srawlins @jacob314

[pq]

Closing in favor of individual tracking issues.