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

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

<!-- Please describe your changes on the following line: -->
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.

---
<!-- Thank you for contributing to Servo! Please replace each `[ ]` by `[X]` when the step is complete, and replace `___` with appropriate data: -->
- [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

<!-- Either: -->
- [X] There are tests for these changes OR

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tests/wpt/metadata/fetch/api/basic/request-forbidden-headers.any.js.ini

@@ -1,23 +0,0 @@
-[request-forbidden-headers.any.html]
-  type: testharness
-  [Accept-Encoding is a forbidden request header]
-    expected: FAIL
-
-  [Access-Control-Request-Headers is a forbidden request header]
-    expected: FAIL
-
-  [Access-Control-Request-Method is a forbidden request header]
-    expected: FAIL
-
-
-[request-forbidden-headers.any.worker.html]
-  type: testharness
-  [Accept-Encoding is a forbidden request header]
-    expected: FAIL
-
-  [Access-Control-Request-Headers is a forbidden request header]
-    expected: FAIL
-
-  [Access-Control-Request-Method is a forbidden request header]
-    expected: FAIL
-

tests/wpt/metadata/fetch/api/headers/header-values-normalize.html.ini

@@ -48,15 +48,6 @@
   [fetch() with value %08]
     expected: FAIL
 
-  [fetch() with value %09]
-    expected: FAIL
-
-  [fetch() with value %0A]
-    expected: FAIL
-
-  [fetch() with value %0D]
-    expected: FAIL
-
   [XMLHttpRequest with value %0E]
     expected: FAIL
 
@@ -164,7 +155,3 @@
 
   [fetch() with value %1F]
     expected: FAIL
-
-  [fetch() with value %20]
-    expected: FAIL
-

tests/wpt/metadata/fetch/api/headers/headers-no-cors.window.js.ini

@@ -1,10 +1,4 @@
 [headers-no-cors.window.html]
-  ["no-cors" Headers object cannot have accept-language/\x01 as header]
-    expected: FAIL
-
-  ["no-cors" Headers object cannot have content-language/\x01 as header]
-    expected: FAIL
-
   ["no-cors" Headers object cannot have content-type set to text/plain;ssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssssss, text/plain]
     expected: FAIL
 

tests/wpt/metadata/fetch/api/request/request-headers.html.ini

@@ -1,5 +0,0 @@
-[request-headers.html]
-  type: testharness
-  [Testing empty Request Content-Type header]
-    expected: FAIL
-

tests/wpt/metadata/fetch/api/response/response-init-002.html.ini

@@ -3,9 +3,6 @@
   [Read Response's body as readableStream]
     expected: FAIL
 
-  [Testing empty Response Content-Type header]
-    expected: FAIL
-
   [Testing null Response body]
     expected: FAIL