Linter: add fixes for fixable canonical lints

[pq]

Add fixes for:

• [x] prefer_typing_uninitialized_variables
• [x] avoid_function_literals_in_foreach_calls
• [ ] avoid_null_checks_in_equality_operators
• [x] avoid_returning_null_for_void
• [x] exhaustive_cases
• [ ] prefer_initializing_formals
• [x] prefer_is_not_operator (covered by an assist)
• [ ] prefer_void_to_null
• [ ] unnecessary_getters_setters
• [x] unnecessary_string_escapes
• [x] unnecessary_string_interpolations (https://github.com/dart-lang/sdk/commit/f9c3c09a9e745e2a261529a2d4fba1dd0b01a25e) cheers @parlough!

See: #2405

[parlough]

@pq Just so I don't overlap with work already being done, any suggestions for one to attempt next?

I was thinking prefer_is_not_operator if no one is currently working on that :)

[bwilkerson]

That one is already covered by an assist. See ConvertIntoIsNot.

It looks like this list didn't take assists into account.

[pq]

It looks like this list didn't take assists into account.

ah... and so maybe I should add that assist processor scraping code to the scorecard after all? 🤔

[pq]

@parlough: if you decide to take a look at one, maybe just post your intention here? I can do the same.

Thanks!

[bwilkerson]

... so maybe I should add that assist processor scraping code to the scorecard after all?

I don't think there's any connection between assists and the lints that they overlap with, so I don't think you can automate that check.

if you decide to take a look at one ...

Just don't forget to try it in the IDE first to see whether there's an assist that applies.

[pq]

I don't think there's any connection between assists and the lints that they overlap with

sorry, right, i meant w/ metadata added to capture that in server source but I think it's overkill. probably better to just track those few exceptions here.

[bwilkerson]

Closing this in favor of the more complete list in https://github.com/dart-lang/sdk/issues/45932. I believe that there were lints added to the core, recommended and flutter lists after this issue was opened, hence the reason the other list is more complete.