feat: on question comment created event

feat: on answer comment created event

feat: add on question best answer chosen domain event

feat: add on answer created domain event

feat: add domain events primitives

feat: add notification subdomain

feat: notification subdomain

feat: implement watched list pattern

feat: more things

First Commit ( •̀ ω •́ )✧

First Commit (✿◡‿◡)