add: pass full=False to dirstate walk
Previously cmdutil.add would call wctx.walk(), which under the hood calls
dirstate.walk with full=True. This means it returns all of the clean files
(which we don't need when computing the add set), as well as the unclean files.
This results in 1) a lot more work being done and 2) this code path
circumventing the hgwatchman extension, resulting in worse performance in
hgwatchman environments ('hg add .' went from 9s to 1.8s).
Hello, Foobar
['Hello, Fo, =;:<o', 'Hello, Bar']