Add types for String.{matchAll,replaceAll} with a well known symbol

[segevfiner]

Fixes #61448

[nmain]

String.prototype.matchAll, when on the [Symbol.matchAll] codepath, just forwards the call to the passed matcher and returns whatever it returns. There's no limitations on the type of the return and no coercion done. Should this then be generic in the return type?

matchAll<T>(matcher: { [Symbol.matchAll](str: string): T; }): T;

[segevfiner]

Wouldn't this apply to all the other [Symbol] RegExp symbols. I don't think it was done for them, it would also make it inconvenient to call, as in the common case, its supposed to return RegExpStringIterator<RegExpMatchArray>, returning something else is technically unexpected, and kinda violates what the symbol is meant to do.

[typescript-bot]

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