errors: introduce InputError and use it from commands and cmdutil This patch introduces a `InputError` class and replaces many uses of `error.Abort` by it in `commands` and `cmdutil`. This is a part of https://www.mercurial-scm.org/wiki/ErrorCategoriesPlan. There will later be a different class for state errors (to raise e.g. when there's an unfinished operation). It's not always clear when one should report an input error and when it should be a state error. We can always adjust later if I got something wrong in this patch (but feel free to point out any you notice now). Differential Revision: https://phab.mercurial-scm.org/D9167

--- a/tests/test-simple-update.t	Wed Oct 21 19:00:16 2020 -0700
+++ b/tests/test-simple-update.t	Tue Oct 06 22:36:15 2020 -0700
@@ -55,7 +55,7 @@
 
   $ hg upd -d foo 0
   abort: you can't specify a revision and a date
-  [255]
+  [10]
 
 update by date
 
@@ -71,7 +71,7 @@
 
   $ hg update -d '>1970-01-01 00:00:02 +0000'
   abort: revision matching date not found
-  [255]
+  [10]
   $ hg update -d '>1970-01-01 00:00:01 +0000'
   found revision 1 from Thu Jan 01 00:00:01 1970 +0000
   1 files updated, 0 files merged, 0 files removed, 0 files unresolved