largefiles: use uipathfn instead of match.{rel,uipath}() (API)

Authored by martinvonz.

Description

largefiles: use uipathfn instead of match.{rel,uipath}() (API)

All callers now pass in a uipathfn, so we can just use that instead of
choosing the right match function. This also means that when we make
add/remove respect ui.relative-paths, it will work for largefiles too.

Differential Revision: https://phab.mercurial-scm.org/D5904