PLT-4167 Team Sidebar (#4569)

* PLT-4167 Team Sidebar

* Address feedback from PM

* change route from my_members to members

* bug fixes

* Updating styles for teams sidebar (#4681)

* Added PM changes

* Fix corner cases

* Addressing feedback

* use two different endpoints

* Bug fixes

* Rename model and client functions, using preferences to store last team and channel viewed

* Fix mobile notification count and closing the team sidebar

* unit test, fixed bad merge and retrieve from cached when available

* bug fixes

* use id for last channel in preferences, query optimization

* Updating multi team css (#4830)

webapp/sass/layout/_module.scss

@@ -10,4 +10,5 @@
 @import 'sidebar-left';
 @import 'sidebar-menu';
 @import 'sidebar-right';
+@import 'team-sidebar';
 @import 'webhooks';