Add gitweb.linkDrafts to control if gitweb links are shown on drafts

If gitweb is hosted on a second server and only public references
are replicated, links to draft patch sets in the panel don't go
anywhere useful.

Default behavior remains the same, to provide links on all patch sets,
regardless of draft status.

Change-Id: Ia26f08b4fd4e480a89b84ff5602603c3fcc8eee6
5 files changed