perf: add a perfphasesremote command
This command measure the time we spend analysing remote phase during push and
pull and display some information relevant to this computation.
The `test-contrib-perf.t` expected output has to be updated but I do need
these module for this perf command.
pager.pager=p0 # $TESTTMP/sysrc:4
ui.editor=e1 # $TESTTMP/userrc:2
pager.pager=p2 # $PAGER
ui.editor=e1 # $TESTTMP/userrc:2