Initialize JS Regex crates and def AST.

[ubugeeei]

ref: #1164

I have initialized a crate for handling JavaScript Regexp and defined the AST.
I implemented the AST while referring to eslint-community/regexpp.

Review Points:

• Is the crate name appropriate?
• Are the crate settings appropriate? (I'm not very sure what should be done.)
• Is the method of defining the AST correct? (Usage of Vex and Box)
• Is the AST definition accurate? (It might be hard to tell if the information is sufficient without implementing a parser or visitor.)
  • Is the documentation appropriate?

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This is my first PR for Rust code to OXC! Please check it out!
Thank you always for your kindness. It's really helpful. 🙏🏻

[Boshen]

Re review points: yes to all questions!

Let's start merging after [lints] get added.

[Boshen]

Nice work! You hands are getting Rusty ;-)