DEV: patchbot: use checked buttons as reference instead of internal table

DEV: patchbot: use checked buttons as reference instead of internal table

The statuses[] table was pre-filled from the shell code during
initialization based on the evaluation and the buttons pre-checked
accordingly, but upon reload, the checked buttons are preserved and
the statuses reinitialized, leading to a different status and color
on lines that were changed.

In practice we don't need this table and we can directly check each
button's state. This makes sure that displayed state is consistent
with checked buttons and allows to preserve the statuses upon reloads
to benefit from updates. Only the start of the review is reset upon
reload now (this allows to consider latest backport state). Of course,
a full reload (shift-ctrl-R) continues to reset the form.