Auto merge of #25358 - pshaughn:looser_header_validation, r=jdm

Header values no longer have to be ASCII or UTF-8

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This passes some failed tests related to header validity when handling ByteStrings outside the printable ASCII range. A few failures remain because the HeaderValue class is stricter than WHATWG/WPT, disallowing various control-code bytes that the spec and tests expect to be allowed.

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- [X] `./mach build -d` does not report any errors
- [X] `./mach test-tidy` does not report any errors
- [X] These changes fix some of the test cases described in #24903

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- [X] There are tests for these changes OR

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