Introduce matrix-appservice-bridge (Matrix application service)
Introduce matrix-appservice-bridge
(Matrix application service). This doesn't have any functionality but is the basic structure for our bridge. Message bridging functionality is being added in https://gitlab.com/gitlab-org/gitter/webapp/-/merge_requests/2042
Part of https://gitlab.com/gitlab-org/gitter/webapp/-/issues/1684
Dev notes
Split out from https://gitlab.com/gitlab-org/gitter/webapp/-/merge_requests/2040
Edited by Eric Eastwood