Include http subdirectory in 'pip cache info' and 'pip cache purge'

[hugovk]

Fixes #8892.

Example:

$ pip cache info
HTTP files location: /Users/hugo/Library/Caches/pip/http
HTTP files size: 1202.4 MB
Number of HTTP files: 2106
Wheels location: /Users/hugo/Library/Caches/pip/wheels
Wheels size: 67.1 MB
Number of wheels: 139

$ pip cache purge
Files removed: 2245

[pradyunsg]

I think this is good to go? I guess I'll wait a bit for more eyeballs on this, but this looks great @hugovk! ^>^

[xavfernandez]

It seems strange that pip cache info now mentions HTTP files but that pip cache list does not provide a way to list them.

[hugovk]

They could be listed, but I'm not sure if is of any practical use.

Here's mine (find /Users/hugo/Library/Caches/pip/http -type f):

list-of-http-files.txt

174 lines like:

/Users/hugo/Library/Caches/pip/http/0/6/d/4/7/06d477c8989727a385fef25a091bf538e3d3ffb7704dd4305590c1aa
/Users/hugo/Library/Caches/pip/http/0/6/e/9/e/06e9e0c4454b68908344d70ef700c97dec1d21c761d561c1c5894080
/Users/hugo/Library/Caches/pip/http/0/6/b/0/0/06b00e550878f90905e993e88197ac4a89508898b31475716f4f8045

And this is after I purged the http cache yesterday. It's now 54.5 MB. Before purging it was 1202.4 MB, so that'd be maybe 4,000 lines like that?

[eamanu]

LGTM

[eamanu]

IMO This is a good PR but I'm not sure if the it closes issue mention it.

[pradyunsg]

Let's gooooo