Auto merge of #14373 - Wafflespeanut:parse, r=emilio

Use the ParserContext along with the Parser

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This changes the `parse` function's signature to include `ParserContext`, so that we don't introduce another trait just for the sake of the context. Instead, we can safely ignore the context whenever we don't need it.

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- [x] `./mach build -d` does not report any errors
- [x] `./mach test-tidy` does not report any errors

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- [x] These changes do not require tests because it's a refactor
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r? @SimonSapin or @emilio or @Manishearth

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