Let WebLink alter image and name depending on what it links from.

By returning a WebLinkInfo from WebLinks instead of the four separate
values, plugins implementing the extension points:
PatchSetWeblink, FileWeblink, BranchWeblink and/or ProjectWeblink
can alter imageUrl, linkName and target depending on what it links
from.

Change-Id: I23716673713db3955d9f1743dee95a87a9db2978
9 files changed