ui: datastore: show comment, allow to edit notes

ui: datastore: show comment, allow to edit notes

the "comment" is the first line of the "notes" field from a manifest,
show it in the grid and allow editing the full notes.

Hack the click event listener a bit together for the right aligned
edit action button, but it works out well and is efficient (only one
event listener is much cheaper than per-buttons ones).

Signed-off-by: Thomas Lamprecht <t.lamprecht@proxmox.com>