completion: complete tags with git tag --delete/--verify

completion: complete tags with git tag --delete/--verify

Completion of tag names has worked for the short -d/-v options since
88e21dc746 ("Teach bash about completing arguments for git-tag",
2007-08-31).  The long options were not added to "git tag" until many
years later, in c97eff5a95 ("git-tag: introduce long forms for the
options", 2011-08-28).

Extend tag name completion to --delete/--verify.

Signed-off-by: Todd Zullinger <redacted>
Signed-off-by: Junio C Hamano <redacted>