dillon1000/react

[rust] Partial handling of identifiers

Fundamentally this PR is about lowering identifiers during construction of HIR. 
For now i'm punting on context variables and assuming all variables are either 
global, module-scoped, or locals. The implementation involves a few pieces: 

* `estree::Identifer` gets extended with optional binding information. The idea 
is that _some_ name resolution mechanism will populate this. Eventually our own, 
but we can also borrow data from another source... 

* `estree-swc` now configures SWC's (possibly broken?) name resolution mechanism 
and sets the above binding data when translating identifiers from swc into our 
estree format. 

* hir `Builder` tracks identifiers based on `(name, BindingId)` pairs, and 
assigns a unique `hir::Identifier` instance for each pair. `Identifiers` are 
clone-able (shared). 

* Tangential: i updated the printer to handle more instruction variants, 
including the now-ported LoadGlobal instr. 

I don't love this but it's a start. Long-term we definitely should have our own 
name resolution mechanism which we run on the estree prior to lowering to HIR.