Implement "defaulted" instantiation arguments

[peterhuene]

If a component being instantiated with a new expression has a unlocked-dep or locked-dep import and the import has not been satisfied by an argument to the new expression, wac should implicitly resolve and instantiate a (shared) instance of the dependency and project into its exports, passing the result as the argument.

Example:

Package foo:bar:

(component
    // ...
   (export "f" (func 0))
)

Package bar:baz:

(component
  (import "unlocked-dep=<foo:bar/f@{>=0.1.0}>" (func))
)

Composition:

let i = new bar:baz { };

Then foo:[email protected] should get resolved and instantiated, f should be aliased from the export, and the alias passed in as the argument for unlocked-dep=<foo:bar/[email protected]>.

The instantiated dependency would either have all of its imports satisfied by implicit imports or by recursively instantiated dependencies for any unlocked-dep and locked-dep imports.

It would be an error if the (transitive) dependencies fail to resolve.