dispatch: move part of callcatch to scmutil Per discussion at 39149b6036e6 [1], we need "callcatch" in worker.py. Move it to scmutil.py to avoid cycles. Note that dispatch's callcatch handles some additional high-level exceptions related to config parsing, and commands. Moving them to scmutil will make scmutil depend on "commands" or require "_formatparse" and "_getsimilar" (and "difflib") to be moved as well. In the worker use-case, it is forked when config and commands are fully loaded. So it should not care about those exceptions. [1]: https://www.mercurial-scm.org/pipermail/mercurial-devel/2016-August/087116.html