Use EntityTitleLookup in EntityIdHtmlLinkFormatter on Repo

Items always link to the main namespace because the formatter uses
an insufficent lookup that simply assumes Items are in the main
namespace. That's wrong in every default installation, e.g. most of
our developers installations.

Again, this is not a perfect solution: this patch ignores the client.
I would like to address this in a following patch, please.

Bug: 62604
Change-Id: I832cf2c58bacc2c6ff8dcd43620a5bca377f120f
Merge "Use EntityTitleLookup in EntityIdHtmlLinkFormatter on Repo"