b4 review feature request - search :)

Hi Konstantin,

It's totally fine to respond to this with 'patches welcome' :) but something
that'd be nice for the b4 review tui mode is being able to fuzzy incremental
search entries, kinda like C-s in emacs.

So maybe default-bind '/' to that and it moves the highlighted entry to one that
contains the searched phrase in submitter or series subject line, or something
simple like that.

Have found myself scanning the list thinking 'hmm I definitely remember b4
review track'ing that but where is it?' :)

Thanks, Lorenzo