Auto merge of #19397 - cbrewster:create_element_for_token, r=jdm,nox

Implement the create an element for token algorithm

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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 #19392 and fix #19393 (github issue number if applicable).

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tests/wpt/metadata/custom-elements/microtasks-and-constructors.html.ini

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-[microtasks-and-constructors.html]
-  expected: CRASH
-  bug: https://github.com/servo/servo/issues/19392

tests/wpt/metadata/custom-elements/parser/parser-fallsback-to-unknown-element.html.ini

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-[parser-fallsback-to-unknown-element.html]
-  expected: CRASH
-  bug: https://github.com/servo/servo/issues/19392