.arcconfig

fileset: add kind:pat operator

":" isn't taken as a symbol character but an infix operator so we can write
e.g. "path:'foo bar'" as well as "'path:foo bar'". An invalid pattern kind
is rejected in the former form as we know a kind is specified explicitly.

The binding strength is copied from "x:y" range operator of revset. Perhaps
it can be adjusted later if we want to parse "foo:bar()" as "(foo:bar)()",
not "foo:(bar())". We can also add "kind:" postfix operator if we want.

One possible confusion is that the scope of the leading "set:" vs "kind:pat"
operator. The former is consumed by a matcher so applies to the whole fileset
expression:

  $ hg files 'set:foo() or kind:bar or baz'
                  ^^^^^^^^^^^^^^^^^^^^^^^^

Whereas the scope of kind:pat operator is narrow:

  $ hg files 'set:foo() or kind:bar or baz'
                                ^^^

{
    "conduit_uri": "https://phab.mercurial-scm.org/api",
    "repository.callsign": "HG",
    "arc.land.onto.default": "@",
    "base": "hg:.^"
}