Feature: Player queue functionality

[nivekyee]

Merge: add event listener for search bar to submit on enter key press Merge: Change rooms-schema to include userCount

• Delete completed song from database and send a refetch signal to client when a song ends
• Automatically play next song after refetch
• Refactor AppContextProvider states and localStorage items (roomName, roomID, roomDesc, password) into an inclusive currentRoom object
• Refactor inconsistent naming (roomid -> roomID)
• Include Player inside Playbar and remove redundant PlayerContextProvider
• Show currentSong info on songInfo card