adapt to "reaction summaries"

[r10s]

• set the stock strings DC_STR_YOU_REACTED and DC_STR_REACTED_BY to reaction_by_you resp. reaction_by_other (may require core update or using core-main, the strings are already on transifex)

• make sure, the chatlist is updated on DC_EVENT_REACTIONS_CHANGED
  (corresponding android pr)

see deltachat/deltachat-core-rust#5387 for details, screenshot and reasoning.

[Simon-Laux]

the strings are already on transifex

Nice

make sure, the chatlist is updated on DC_EVENT_REACTIONS_CHANGED
(deltachat/deltachat-android#2986)

If the chatlist events core pr is ready to be merged and contains this, then this point will be addressed by #3268