Add ability to export data for a given room

Add ability to export data for a given room

Same concept as what we are doing for exporting data for a given user in https://gitlab.com/gitlab-org/gitter/webapp/-/issues/1899

Export endpoints

• Messages -> https://gitlab.com/gitlab-org/gitter/webapp/-/merge_requests/1990
• Room members -> https://gitlab.com/gitlab-org/gitter/webapp/-/merge_requests/1999
• Room integration events -> https://gitlab.com/gitlab-org/gitter/webapp/-/merge_requests/2002
• Bans -> https://gitlab.com/gitlab-org/gitter/webapp/-/merge_requests/2003