Add JSDoc type annotations

[y-hsgw]

I have added type annotations and fixed associated type errors.

[ljharb]

this isn't just adding type annotations and a lot of the changes are potentially breaking.

[y-hsgw]

I have addressed this in pull request #3732 and will proceed to close this one. I'll handle the areas requiring type changes separately.

[ljharb]

I would prefer to update this PR with those changes rather than abandoning it.

[ljharb]

i only went like 20% through, but this should help you refine the entire thing

[codecov]

Codecov Report

Attention: Patch coverage is 98.88889% with 1 line in your changes missing coverage. Please review.

Project coverage is 97.64%. Comparing base (cef8123) to head (4467e3a).
Report is 6 commits behind head on master.

Files	Patch %	Lines
lib/rules/no-unused-class-component-methods.js	50.00%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master    #3731      +/-   ##
==========================================
+ Coverage   97.62%   97.64%   +0.01%     
==========================================
  Files         134      134              
  Lines        9617     9662      +45     
  Branches     3488     3514      +26     
==========================================
+ Hits         9389     9434      +45     
  Misses        228      228              

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[ljharb]

Please rebase this PR, and extract any changes that aren't about whitespace/parens, or adding/editing comments, to separate commits - and then all the "type annotations" changes can be in a single commit i can review separately. Thanks!

[y-hsgw]

I have rebased and cleaned up the commits. Please check.

[ljharb]

I've gone ahead and updated this to remove all the breaking changes. The way to safely resolve TypeScript's inability to understand that an x.foo check is identical to 'foo' in x && x.foo semantically is not to hardcode AST node types (that a custom parser might not match) but to add 'foo' in x and let TS do the narrowing.

[voxpelli]

This caused a regression, see #3819

It should always return when callee.object.type is not 'ThisExpression' – no matter if 'name' is missing in callee.property or not.

The functionality before this PR would be equivalent to this type checker compliant check:

        if (
          callee.object.type !== 'ThisExpression' ||
          !('name' in callee.property) ||
          callee.property.name !== 'isMounted'
        ) {

[voxpelli]

PR with said fix: #3821