[MM-39583] - Intermediary web login page: Workspace Cookies (#19256)

* [MM-39583] - Intermediary web login page: Workspace Cookies

* only cloud

* fix error with license check

* feedback impl

* improvement

* make improvements

Co-authored-by: Mattermod <mattermod@users.noreply.github.com>

api4/user.go

@@ -1852,6 +1852,11 @@ func login(c *Context, w http.ResponseWriter, r *http.Request) {
 		c.App.AttachSessionCookies(c.AppContext, w, r)
 	}
 
+	// For context see: https://mattermost.atlassian.net/browse/MM-39583
+	if c.App.Srv().License() != nil && *c.App.Srv().License().Features.Cloud {
+		c.App.AttachCloudSessionCookie(c.AppContext, w, r)
+	}
+
 	userTermsOfService, err := c.App.GetUserTermsOfService(user.Id)
 	if err != nil && err.StatusCode != http.StatusNotFound {
 		c.Err = err