tests: add tests for matching keyword

This adds a couple of tests for the revset "matching" keyword:

1. Test that the 2nd parameter is optional
2. Test that all the 1st argument can be a revset and that all the supported
fields of the 2nd argument work.

tests/test-revset.t

@@ -292,6 +292,11 b' quoting needed'
   6
   $ log 'limit(head(), 1)'
   0
+  $ log 'matching(6)'
+  6
+  $ log 'matching(6:7, "phase parents user date branch summary files description substate")'
+  6
+  7
   $ log 'max(contains(a))'
   5
   $ log 'min(contains(a))'