Add evacuateUser endpoint, use it when deactivating accounts (#2545)

* Add `evacuateUser` endpoint, use it when deactivating accounts

* Populate the API

* Clean up user devices when deactivating

* Include invites, delete pushers

roomserver/api/perform.go

@@ -223,3 +223,12 @@ type PerformAdminEvacuateRoomResponse struct {
 	Affected []string `json:"affected"`
 	Error    *PerformError
 }
+
+type PerformAdminEvacuateUserRequest struct {
+	UserID string `json:"user_id"`
+}
+
+type PerformAdminEvacuateUserResponse struct {
+	Affected []string `json:"affected"`
+	Error    *PerformError
+}