Initialize JS Regex crates and def AST. (#1500)

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](https://github.com/eslint-community/regexpp/blob/2e8f1af992fb12eae46a446253e8fa3f6cede92a/src/ast.ts).

crates/oxc_js_regex/Cargo.toml

@@ -0,0 +1,23 @@
+[package]
+name                   = "oxc_js_regex"
+version                = "0.0.0"
+publish                = false
+authors                = ["Ubugeeei <[email protected]>"]
+categories.workspace   = true
+description.workspace  = true
+edition.workspace      = true
+homepage.workspace     = true
+keywords.workspace     = true
+license.workspace      = true
+repository.workspace   = true
+rust-version.workspace = true
+
+[lints]
+workspace = true
+
+[lib]
+doctest = false
+
+[dependencies]
+oxc_allocator = { workspace = true }
+oxc_span      = { workspace = true }

crates/oxc_js_regex/README.md

@@ -0,0 +1,5 @@
+# oxc_js_regex
+
+⚠️ Work in progress. Do not use yet.
+
+see: https://github.com/oxc-project/oxc/issues/1164