Fix WIT sugar for resource names being own<T>

[alexcrichton]

This commit fixes an issue where WIT resources should not have to be
wrapped in own<T> but instead are allowed to be defined as just T.
This is a bit tricky when T is defined in a foreign package since the
"inject the own wrapper" isn't apparent during parsing but only later
once packages are merged together. This phase has been updated
accordingly to inject own wrappers as necessary.

Note: this builds on #1079 as the first commit

[alexcrichton]

Fuzzing ended up showing a number of other issues with this commit, so I've addressed those now in a follow-up commit in the middle here. I can't add most of the fuzz test cases here yet since they require more support in wit-component, but they should all be included in a subsequent PR which fills out wit-component.

@sunfishcode could you double-check the new commits here though? They're new-enough I don't want to carry over the review of the first commit to them too

[silesmo]

This looks good! I like how you changed it to handle resolving the own handles in the same way regardless of how it's used, removing the need to do it in the Name resolution as well as in other places.

[alexcrichton]

@sunfishcode to confirm, would you be ok if I carried over #1084 (review) to here?

[sunfishcode]

Yes, that's good.