Compact string with precomputed hash

[Boshen]

We are commonly hashing Atoms when e.g. building scope tree. Possibly could avoid repeated hashing and memory accesses by storing hash inline in Atom.

Rolldown wants this.

[rzvxa]

Isn't this just a duplicate of https://github.com/oxc-project/backlog/issues/46#issuecomment-2200571540

[Boshen]

Yes, that issue is for a overhaul of the Atom type, where this is just a wrapped type, which should be done separately as two tasks.

[rzvxa]

Yeah sorry for the comment, I came to this conclusion after sending that comment so that's why I marked it as resolved.

[overlookmotel]

Related to #46.