MatrixRTC: move MatrixRTCSession logic into LocalMembershipManager#4608

toger5 merged 9 commits intodevelopmatrix-org/matrix-js-sdk:developfrom

toger5/refactor-matrixrtcsession-part3.5-seperate-myMembershipManagermatrix-org/matrix-js-sdk:toger5/refactor-matrixrtcsession-part3.5-seperate-myMembershipManagerCopy head branch name to clipboard