fast-import: add 'abort-if-invalid' mode to '--signed-tags=<mode>'
In git-fast-import(1), the 'abort-if-invalid' mode for the
'--signed-commits' option verifies commit signatures during import and
aborts the entire operation when verification fails. Extend the same
behavior to signed tag objects by introducing an 'abort-if-invalid' mode
for the '--signed-tags' option.
Signed-off-by: Justin Tobler <jltobler@gmail.com> Signed-off-by: Junio C Hamano <gitster@pobox.com>