Avoid collecting resources-as-we-go in favor of doing that more
declaratively elsewhere. Additionally handle imported-vs-exported
resource via the order that interfaces are visited.

* Use `&mut self` instead of `StoreContextMut`
* Make resource traits as supertraits of the `Host` trait generated for
  each resource.
* More uniformly handle types/returns with resource methods.
* Fix derivations of `Clone` and `Copy` for where handles are contained.

Updates to host resources and `bindgen!`

resources in exported functions arguments break with this commit and will be fixed in following commits.

This is now the same as the preexisting `generate_function_trait_sig`

This determination happens by looking up the origin definition of a
resource, not the leaf possibly-aliased type.

Resources don't have their representation asserted since the bare type
itself doesn't implement `ComponentType`, but otherwise generate type
aliases the same way as other type aliases.

No need to update `wit-bindgen` to 0.10.0 just yet, that'll happen in a
future update if necessary.

More resources-related changes