When reporting candidate location, handle cached wheels better

[pfmoore]

Can we use the original link w/ (cached) in the name in that case?

OK to do this in a follow up, if you file an issue to aggregate all the call sites that print req.link.

Originally posted by @pradyunsg in #8394

[pradyunsg]

For context, this is the relevant comment: #8394 (comment)

[brainwane]

I just spoke with Pradyun.

Currently, when a user gets a Resolution Conflict error or similar, if pip grabbed one of the packages from local cache, the output that the user sees is very very lengthy, which does not feel polished. It would make more sense to print the name of the package and then the string " (cached)" or something like that, as in:

python-social-auth (cached)

This seems like a polish issue rather than a problem that needs solving before the 20.3 release in October.

I'm not sure how "call sites that print req.link" are related to this but I presume that they are because of #8394 (comment) .

[uranusjr]

Note for future contributors: Some logic in #7898 would be useful for this.