status: introduce higher-level ui.relative-paths
The existing commands.status.relative trumps the new config. We need
to keep the existing config around for compatibility. However, I don't
think we need to introduce similar command-specific options for other
commands when they learn to respec ui.relative-paths.
Differential Revision: https://phab.mercurial-scm.org/D5746
max_width = 79
wrap_comments = true
error_on_line_overflow = true