We mostly use `allocator` as var name for an `Allocator`, but in some places used the shorter name `alloc`. Use `allocator` everywhere for consistency.
This PR renames the `oxc_ast_codegen` crate to `oxc_ast_tools`, It improves the readability and organization of the codebase by giving the crate a name that better reflects its purpose and contents.
It also improves the error message in CI.
