feat!: clear non-oneshot output chord on next action

[jtroo]

This commit changes output chord behavior to be more user-friendly by
clearing output chord keys on the next action. I have also been told
(though have not confirmed) that QMK has similar behaviour. I am not
sure that the change in this commit replicates QMK's behaviour
perfectly, but it seems good enough.

Clearing output chord keys on the next action allows a subsequent typed
key to not have modifiers pressed alongside it. Without this change,
typing a new key without first releasing an output chord can have the
unintended typing result. Users have asked about this few times in
issues/discussions and the current workaround is to use a macro.
However, this can be hard to discover. Some users may just be living
with the annoyance because aren't aware that there is a workaround and
they haven't asked.

Output chords within a one-shot are ignored because someone might do
something like (one-shot C-S-lalt) to get 3 modifiers within a
one-shot action. These are probably intended to remain held. However,
other output chords are usually used to type symbols or accented
characters, e.g. S-1 or RA-a. If the symbol or accented character is
held down, key repeat works just fine because OS key repeats are not
keyberon actions.

Checklist

• Add documentation to docs/config.adoc
  • Yes
• Add example to cfg_samples/kanata.kbd
  • N/A
• Update error messages
  • N/A
• Added tests, or did manual testing
  • Yes