dillon1000/react

Construct LoadGlobal; consume hook info from types

Updates BuildHIR to produce LoadGlobal instructions for references to globals. 
Note that this breaks our previous strategy of finding hook calls: that relied 
on looking at the callee of a CallExpression and checking its name, which relied 
on the callee not being lowered to a temporary. By lowering the name (eg 
`useState`) to a temporary first, we now no longer see the name at the callsite. 

Thankfully @gsathya solved this for us already by teaching type inference about 
hooks, and more generally implementing type inference. I updated this so that we 
infer the type of a LoadGlobal if the name is a hook: the type inference picks 
this up and propagates the type forward correctly. So now, all places that 
needed to check for a hook can just look at the type and everything works. 

This is much more robust than before - you can now reassign a hook to a local 
variable and we'll still detect that when you call it, you're calling a hook.