Expose tag and commit hash separately to user

[mentonin]

On tables that show trees (e.g. /tree), we can sort and search by commit hash or tag, but the hash is only shown if the commit has no tag;

I suggest exposing both to the user (using abbreviated commit hash, probably), allowing sort by tag only (commit hash sorting is hardly useful), filtering by tagged commits, and visual verification that the displayed commit has the correct hash.

[mentonin]

For tag sorting:

• Sort version tags by version semantics
• Sort alphabetically if version could not be determined
• Display version tags before non-version tags when sorting by tags