* wiggle-generate: paramaterize library on module path to runtime
This change makes no functional difference to users who only use the
wiggle crate.
Add a parameter to the `Names` constructor that determines the module
that runtime components (e.g. GuestPtr, GuestError etc) of wiggle come
from. For `wiggle` users this is just `quote!(wiggle)`, but other
libraries which consume wiggle-generate may wrap and re-export wiggle
under some other path, and not want their consumers to have to know
about the wiggle dependency, e.g. `quote!(my_crate::some_path::wiggle)`.
* wiggle-generate,macro: move more logic into macro
better for code reuse elsewhere
25cbd8b591