Emitted JS / Gentype double-escapes output

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When using the @as attribute with a value containing escape sequences (e.g., @as("with\"dquote")), the generated JavaScript incorrectly double-escapes the string. Additionally the parser can't handle exotic identifiers with a \".

I found this while looking at #8086 and removing String.escaped from this line:

https://github.com/rescript-lang/rescript/blob/14721cb26f727e20fa834dbcce28fb439ad2e006/compiler/gentype/TranslateTypeDeclarations.ml#L48

This existing test with an escaped double-quote \" in the @as annotation

https://github.com/rescript-lang/rescript/blob/14721cb26f727e20fa834dbcce28fb439ad2e006/tests/gentype_tests/typescript-react-example/src/Records.res#L125-L139

Results it being double-escaped in the generated typescript types and javascript:

https://github.com/rescript-lang/rescript/blob/14721cb26f727e20fa834dbcce28fb439ad2e006/tests/gentype_tests/typescript-react-example/src/Records.gen.tsx#L51-L58

https://github.com/rescript-lang/rescript/blob/14721cb26f727e20fa834dbcce28fb439ad2e006/tests/gentype_tests/typescript-react-example/src/Records.res.js#L106-L115

There's also a parser bug:

https://github.com/illusionalsagacity/rescript-compiler/blob/3293dcb812e416afccb0900df933bbbb533578f2/tests/gentype_tests/typescript-react-example/src/Records.res#L125-L142

Error in @tests/gentype-react-example:

  Syntax error!
  /rescript-compiler/tests/gentype_tests/typescript-react-example/src/Records.res:135:11-17

  133 ┆ @as("with\"dquote")
  134 ┆ withDQuote: string,
  135 ┆ \"with\"dquote2": string,
  136 ┆ @as("with'squote")
  137 ┆ withSQuote: string,

  Did you forget a `,` here?

Start at compiler/gentype/TranslateTypeDeclarations.ml around line 48, then inspect the @as cases in tests/gentype_tests/typescript-react-example/src/Records.res and their generated .gen.tsx and .res.js outputs. Run the existing gentype test and reproduce both escaped-quote cases. Done means the generated JavaScript and TypeScript do not double-escape the value and the parser accepts the exotic identifier.