Add ImportResolver interface and use it for global imports

[stevenfontanella]

Add an ImportResolver interface with some implementations to handle the spec interpreter and ctor-eval

• Removes coupling of imported names from the module they come from. This will allows us to provide special imports like the spec test module better which have some 'magic' e.g. for printing functions which can't be implemented in Wasm (globals remain the same because they still come from a real module which is better).
• Removes pointer chasing logic when resolving imported globals in both cases.
• Also allows us to relax ctor-eval and allow programs that import globals to be optimized more (as long as they don't try to evaluate imports) Try allowing globals to be imported in ctor eval #8168
• Fixes Segfault in ctor-eval when an imported global isn't used #8167