completion: bisect: recognize but do not complete view subcommand

completion: bisect: recognize but do not complete view subcommand

The "view" alias for the visualize subcommand is neither completed nor
recognized.  It's undesirable to complete it because it's first letters
are the same as for visualize, making completion less rather than more
efficient without adding much in the way of interface discovery.
However, it needs to be recognized in order to enable log option
completion for it.

Recognize but do not complete the view command by creating and using
separate lists of completable_subcommands and all_subcommands.  Add
tests.

Signed-off-by: Britton Leo Kerin <britton.kerin@gmail.com>
Signed-off-by: Junio C Hamano <gitster@pobox.com>