PLT-5080 (Server): Channel-Admin level permissions (#4874)

Adds permissions for manage/delete public/private channels at the
Channel Admin level.

utils/authorization.go

@@ -31,6 +31,12 @@ func SetDefaultRolesBasedOnConfig() {
 			model.PERMISSION_MANAGE_PUBLIC_CHANNEL_PROPERTIES.Id,
 		)
 		break
+	case model.PERMISSIONS_CHANNEL_ADMIN:
+		model.ROLE_CHANNEL_ADMIN.Permissions = append(
+			model.ROLE_CHANNEL_ADMIN.Permissions,
+			model.PERMISSION_MANAGE_PUBLIC_CHANNEL_PROPERTIES.Id,
+		)
+		break
 	case model.PERMISSIONS_TEAM_ADMIN:
 		model.ROLE_TEAM_ADMIN.Permissions = append(
 			model.ROLE_TEAM_ADMIN.Permissions,
@@ -46,6 +52,12 @@ func SetDefaultRolesBasedOnConfig() {
 			model.PERMISSION_DELETE_PUBLIC_CHANNEL.Id,
 		)
 		break
+	case model.PERMISSIONS_CHANNEL_ADMIN:
+		model.ROLE_CHANNEL_ADMIN.Permissions = append(
+			model.ROLE_CHANNEL_ADMIN.Permissions,
+			model.PERMISSION_DELETE_PUBLIC_CHANNEL.Id,
+		)
+		break
 	case model.PERMISSIONS_TEAM_ADMIN:
 		model.ROLE_TEAM_ADMIN.Permissions = append(
 			model.ROLE_TEAM_ADMIN.Permissions,
@@ -76,6 +88,12 @@ func SetDefaultRolesBasedOnConfig() {
 			model.PERMISSION_MANAGE_PRIVATE_CHANNEL_PROPERTIES.Id,
 		)
 		break
+	case model.PERMISSIONS_CHANNEL_ADMIN:
+		model.ROLE_CHANNEL_ADMIN.Permissions = append(
+			model.ROLE_CHANNEL_ADMIN.Permissions,
+			model.PERMISSION_MANAGE_PRIVATE_CHANNEL_PROPERTIES.Id,
+		)
+		break
 	case model.PERMISSIONS_TEAM_ADMIN:
 		model.ROLE_TEAM_ADMIN.Permissions = append(
 			model.ROLE_TEAM_ADMIN.Permissions,
@@ -91,6 +109,12 @@ func SetDefaultRolesBasedOnConfig() {
 			model.PERMISSION_DELETE_PRIVATE_CHANNEL.Id,
 		)
 		break
+	case model.PERMISSIONS_CHANNEL_ADMIN:
+		model.ROLE_CHANNEL_ADMIN.Permissions = append(
+			model.ROLE_CHANNEL_ADMIN.Permissions,
+			model.PERMISSION_DELETE_PRIVATE_CHANNEL.Id,
+		)
+		break
 	case model.PERMISSIONS_TEAM_ADMIN:
 		model.ROLE_TEAM_ADMIN.Permissions = append(
 			model.ROLE_TEAM_ADMIN.Permissions,