Insert repeat will now only record non-synthesized keys, and when played back
execute mappings as well. Constructing some tests, and with the specific goal
of fixing https://github.com/alexherbo2/auto-pairs.kak/issues/38, this appeared to
be the best approach. Other options could be evaluating the maps only when recording,
but this gave other issues (see tests/normal/repeat-insert/repeat-insert-mapped)

At this point, repeat-insert may be essentially just a hardcoded macro, at least I
haven't identified the difference. If this really is the case, it may make sense to
give it a dedicated register, and implement it as a macro.

Fixes #3600

`a` will just jump on next line, `a` on last end of line opens a new
line beneath it.

Fixes #1164