upgrade: support the --quiet flag
The command is currently very verbose with a various bit of output being time
sensitive or randomized. The make invocation bulky and hard to match in the
test. We move various message from `ui.write` to `ui.status` in order for the
`--quiet` flag to have effect and helps the situation.
As a side benefit, we can replace the various redirection to > /dev/null with the --quiet flag.
Differential Revision: https://phab.mercurial-scm.org/D8429
$ hg init
$ touch unknown
$ touch a
$ hg add a
$ hg ci -m "1"
$ touch b
$ hg add b
$ hg ci -m "2"
Should show unknown
$ hg status
? unknown
$ hg revert -r 0 --all
removing b
Should show unknown and b removed
$ hg status
R b
? unknown
Should show a and unknown
$ ls -A
.hg
a
unknown