feat(JitsiConference): add 'getConnection' getter
feat(JitsiConference): add 'getConnection' getter

Adds a getter to retrieve JitsiConnection instance used by
the JitsiConference.

damencho/lib-jitsi-meet,jiyeyuran/lib-jitsi-meet,jitsi/lib-jitsi-meet,jitsi/lib-jitsi-meet