🏗️ refactor(architecture): move events from write slices packages to dedicated one for between slices contracts

[MateuszNaKodach]

Change caused by LinkedIn discussion:
https://www.linkedin.com/feed/update/urn:li:activity:7295062961356771328?commentUrn=urn%3Ali%3Acomment%3A%28activity%3A7295062961356771328%2C7295089102633263104%29&dashCommentUrn=urn%3Ali%3Afsd_comment%3A%287295089102633263104%2Curn%3Ali%3Aactivity%3A7295062961356771328%29

I've given it more thought recently, and indeed events extracted from slices can be more flexible (to do not couple them to their sourced command slice, but treat as API between slices).

Especially in cases where the same event can be triggered by two different commands (although this doesn't happen very frequently).
I have a case in the project, where I think I should refactor handling the RecruitCreature. It should result in two events CreatureRecruited and AvailableCreaturesChanged instead of just the first one. Then in event handlers to reduce available creatures, I will just handle AvailableCreaturesChanged instead of both.

What I would potentially modify is to extract the events separately, as a contract (system backbone) between slices, while keeping the rest as it was. The Aggregate and Commands would stay in the write package, as they're only shared between write slices. Rest API, external consumers and commands will be also in the same package, do not spread one slice through "layers" like "domain/application".

Of course, everything I mean in the scope of a single Bounded Context.