Add metric warning support (announcement bar and DM) (#14483)

* Admin. Advisory: Add warning for number of active users metric status

Co-authored-by: Catalin Tomai <catalin.tomai@mattermost.com>

web/params.go

@@ -78,6 +78,7 @@ type Params struct {
 	FilterAllowReference      bool
 	FilterParentTeamPermitted bool
 	CategoryId                string
+	WarnMetricId              string
 }
 
 func ParamsFromRequest(r *http.Request) *Params {
@@ -316,5 +317,9 @@ func ParamsFromRequest(r *http.Request) *Params {
 		params.IncludeDeleted = val
 	}
 
+	if val, ok := props["warn_metric_id"]; ok {
+		params.WarnMetricId = val
+	}
+
 	return params
 }