Set both background and foreground color when displaying help bar to
avoid sitation where default foreground color used by terminal is hard
to read on blue background (like cyan on blue or black on blue).

Apply colors to whole generated help bar to avoid 'stripes' of different
background color where whitespace is used between help items.

The rendering of color for 'No description provided' text is broken on
bright terminals - it sets black background which together with default
black forground color renders opaque rectangle.

The GreyBold color alias is broken too - name suggests bold gray
forground color, but actually sets bold default fg color with black
bacground.

First make color alias consistent. Rename it to BlackBold and have it
set bold black fg color (same as similar *Bold aliases).

Second, update all places which use it to render text to also use white
background to prevent it from disappering in terminals with black
background color.