[CLD-6537] Cloud Annual Renewals - Banners Implementation (#25267)

* Initial implementation of Cloud Annual Renewal flow - system banners for admins and end users

* Actually add the file

* Add AlertBanner to system console billing_subscriptions page

* Fixes for non-admin banner and pipeline

* Updates to coincide with the CWS side of thigns

* Add a feature flag for the 60 day experience to ensure banners don't show accidentally

* Fix tests

---------

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

server/public/model/feature_flags.go

@@ -46,6 +46,8 @@ type FeatureFlags struct {
 
 	CloudIPFiltering bool
 	ConsumePostHook  bool
+
+	CloudAnnualRenewals bool
 }
 
 func (f *FeatureFlags) SetDefaults() {
@@ -63,6 +65,7 @@ func (f *FeatureFlags) SetDefaults() {
 	f.StreamlinedMarketplace = true
 	f.CloudIPFiltering = false
 	f.ConsumePostHook = false
+	f.CloudAnnualRenewals = false
 }
 
 // ToMap returns the feature flags as a map[string]string