…ce, r=estebank

Add warning when whitespace is not skipped after an escaped newline

Fixes issue rust-lang#87318, also simplifies issue rust-lang#87319.

* Add support to the lexer to emit warnings as well as errors.
* Emit a warning when a string literal contains an escaped newline, but when (some of) the whitespace on the next line is not skipped due to it being non-ASCII.

Rollup of 9 pull requests

Successful merges:

 - rust-lang#86072 (Cross compiling rustc_llvm on Darwin requires zlib.)
 - rust-lang#87385 (Make `SEMICOLON_IN_EXPRESSIONS_FROM_MACROS` warn by default)
 - rust-lang#87547 (Add missing examples for NonNull)
 - rust-lang#87557 (Fix issue with autofix for ambiguous associated function from Rust 2021 prelude when struct is generic)
 - rust-lang#87559 (Tweak borrowing suggestion in `for` loop)
 - rust-lang#87596 (Add warning when whitespace is not skipped after an escaped newline)
 - rust-lang#87606 (Add some TAIT-related regression tests)
 - rust-lang#87609 (Add docs about performance and `Iterator::map` to `[T; N]::map`)
 - rust-lang#87616 (Fix missing word in rustdoc book)

Failed merges:

r? `@ghost`
`@rustbot` modify labels: rollup

…whitespace, r=estebank"

This reverts commit aa9e6aa, reversing
changes made to 5e2655d.