Repositories view: instead of showing the checked out ID show a nice name, e.g. "<tag> +1" [SG-8069]

In pane Repositories, next to a repository (also true for submodules) the branch that is checked out is displayed, and the tooltip shows additional information about this branch.

When HEAD is pointing to a commit (no local branch present; 'read-only' checkout), the information displayed is very limited, being the commit ID and commit summary. Also the tooltip shows only few information.

Instead of

    Repository_name (short_SHA: commit_summary)

it would be great to have tag information displayed here if present, e.g.

    Repository_name (chronological list of tags)

and move the

    short_SHA: commit_summary

to the tooltip. The tags could also be added to the tooltip, one per line.

With this information I would be possible to immediately see for a repository using submodules which submodule versions are used (assuming that the submodule commits have been properly tagged).