Premium SKU (#30396)

* Added premium SKU

* removed duplicate enterprise license check functions

* Added license check on API layer

* lint fix

* lint fix

* refactured signature:

* test: Add comprehensive tests for license tier check functions

* fixed test

* text update

* optimised license checks

* fixedf test

* Updated license valid function

* webapp license checks

* handling prekium SKU in webappp:

* added plugin api method and general refactoring

* Updated tests

---------

Co-authored-by: Mattermost Build <build@mattermost.com>

server/config/client.go

@@ -226,7 +226,7 @@ func GenerateClientConfig(c *model.Config, telemetryID string, license *model.Li
 			props["ExperimentalRemoteClusterService"] = strconv.FormatBool(c.FeatureFlags.EnableRemoteClusterService && *c.ConnectedWorkspacesSettings.EnableRemoteClusterService)
 		}
 
-		if license.SkuShortName == model.LicenseShortSkuProfessional || license.SkuShortName == model.LicenseShortSkuEnterprise {
+		if model.MinimumProfessionalLicense(license) {
 			props["EnableCustomGroups"] = strconv.FormatBool(*c.ServiceSettings.EnableCustomGroups)
 			props["PostAcknowledgements"] = "true"
 			props["ScheduledPosts"] = strconv.FormatBool(*c.ServiceSettings.ScheduledPosts)