Intelligent loading

If only precise roots are defined, namely without wildcards, instead of loading everything and parsing everything part on the proto source/path, once Wire found the type, it could do a kinda breadth search going through the imports of the proto file where the roots were found.
Another approach would be to, regardless of the roots, define "include roots" that Wire has to load. Then if necessary, it would go through the imports to resolve the type it wants to resolve.

The point would be that someone would not have to define in includes all the files that are required to load a schema, but at the same time without having Wire to load the whole proto source because if too big, it takes a lot of time.

The issue names no files, tests, or entry points. Start by tracing how Wire loads proto sources, applies precise roots and includes, and follows imports; compare import traversal with explicit include roots. Done means required imported types resolve without loading and parsing the entire proto source.