refactor(rome_syntax): improve inner_string_text

[Conaclos]

Summary

This PR improves the concistency of the code-base. It introduces several changes:

• Remove QuotedString and StaticStringValue in favor of TokenText and StaticValue.
  This removes a bug in the implementation of QuotedString that was not reported yet.
• Remove unused functions related to these types
• Simplify StaticValue by replacing TemplateChunk with String and EmptyString
  • I removed dead (and misleading) code (comparison against -0 and +0 has no sense because we only handle positive numbers...)
  • I removed recognition of template string such as "${1}" because this leads to erroneous string values (for instance ${1n} is converted to the string 1n instead of the string 1).

There is more refactoring to do (maybe removing StaticValue in favor of an union of AST nodes). However, there are already many changes. This seems enough for this PIR.

Test Plan

Updated and new doc-tests.

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[ematipico]

The best code is less code!

Amazing refactors and cleaner code. You're amazing 🚀

I left some questions and suggestions but overall we can merge it.

[Conaclos]

The best code is less code!

As Antoine de Saint-Exupéry said:

La perfection est atteinte, non pas lorsqu'il n'y a plus rien à ajouter, mais lorsqu'il n'y a plus rien à retirer.

Meaning: "Perfection is achieved, not when there is nothing more to add, but when there is nothing left to take away."