[Refactor] SSE 훅을 Provider로 통합, unReadCount 전역상태에서 제거#394

Chiman2937 merged 3 commits intomainWeGo-Together/WeGo_FrontEnd:mainfrom

chiyoung-refactor/notification-stateWeGo-Together/WeGo_FrontEnd:chiyoung-refactor/notification-stateCopy head branch name to clipboard