JS: Address some code that weren't affecting any query result

[erik-krogh]

As a followup to #8347 I checked if some code had become dead.
There was no new dead code, but I found some interesting things regardless.

1. Some code doesn't affect query result.
   That is partly expected (e.g. a lot of classes in Expr.qll/TypeScript.qll are not used anywhere).
   But there were also some unexpected result, like a few Sanitizer classes that weren't referenced anywhere.
2. Code that was already dead. That is, code that doesn't affect any query, and isn't referenced by any public API.
   (Not this PR, I'll address that in another PR).

This query partially addresses 1) in JS.
There's still plenty of code that doesn't affect any query, but all the remaining seems benign.

[esbena]

Interesting findings. Thanks once again for doing this kind of cleanup!

One nit: Should all of the deprecations have a qldoc string pointing the users to the alternative?

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Also, please confirm that https://github.com/github/codeql/blob/4fc85a791d45d931ec6dac0304e8c314eb0ba23a/javascript/ql/test/library-tests/Classes/tests.ql contains the inlined query predicate version of the files deleted in 5e52a71.

[erik-krogh]

One nit: Should all of the deprecations have a qldoc string pointing the users to the alternative?

👍

Also, please confirm that https://github.com/github/codeql/blob/4fc85a791d45d931ec6dac0304e8c314eb0ba23a/javascript/ql/test/library-tests/Classes/tests.ql contains the inlined query predicate version of the files deleted in 5e52a71.

Confirmed 👍

[esbena]

We need a change note for the same reason as in #8323 (comment):

If people are going to start seeing deprecated warnings they weren't seeing before, this definitely requires a change note.