errors: make InterventionRequired subclass Abort
The docstring for `Abort` says that it's for errors raised by commands
and `InterventionRequired` is definitely something raised by commands,
so it seems that it should be an `Abort`. This patch makes it so. It
adds a `coarse_exit_code` (in addition to the already existing
`detailed_exit_code`) to `Abort` to achieve that, since
`InterventionRequired` should result in a special exit code even when
the `ui.detailed-exit-code` config is not set.
Differential Revision: https://phab.mercurial-scm.org/D10737
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