Array method definition revamp: Use case collection

We've gotten numerous issue reports and PRs to change the methods of Array, particularly reduce, map, and filter. The built-in test suite doesn't cover these very well, and these methods interact with each other and the surrounding contextual type in fairly subtle ways.

@jablko has done a great job at #33645 collecting a variety of issues into a single PR; we need to augment this PR (or something like this) with a proper test suite so we can be sure about what's being changed.

I'd like to create a clearinghouse issue here to collect self-contained (I CANNOT POSSIBLY STRESS THIS ENOUGH, SELF-CONTAINED, DO NOT IMPORT FROM RXJS OR WHAT HAVE YOU) code samples that make use of the array methods.

Please include with your snippet:

• Compiler settings
• Compiler version you were testing with
• The expected behavior (examples that should and should not produce errors are both useful)
• No imports or exports; snippets need to be self-contained so that we can put them into our test suite without extra complications

Once we've established a critical mass of code snippets, we can start combining the existing PRs into an all-up revamp and assess its impact to real-world code suites to figure out which changes don't result in unacceptable breaking changes.

ｓｅｌｆ－ｃｏｎｔａｉｎｅｄ

まず issue #36554 に収集された例と関連する PR #33645 を確認し、Array メソッドの reduce、map、filter に焦点を当てます。コンパイラー設定、コンパイラーのバージョン、期待される診断を含む自己完結型のスニペットのみを追加してください。提案された刷新の指針となる、十分に幅広いテストコレクションが存在すれば完了です。