add: fix subrepo recursion for explicit path handling
When support for handling explicit paths in subrepos was added to the add
command (9e99d2bbb1b1), subrepo recursion wasn't taken into account. This
change adds an explicitonly argument to cmdutil.add to allow controlling which
levels of recursion should include only explicit paths versus all matched
paths.
requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 4 changes to 4 files
updating to branch default
4 files updated, 0 files merged, 0 files removed, 0 files unresolved
requesting all changes
adding changesets
adding manifests
adding file changes
added 1 changesets with 4 changes to 4 files
updating to branch default
4 files updated, 0 files merged, 0 files removed, 0 files unresolved