[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

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

server/channels/api4/cloud_test.go

@@ -154,7 +154,7 @@ func Test_GetSubscription(t *testing.T) {
 		ProductID:       "SomeProductId",
 		AddOns:          []string{},
 		StartAt:         0,
-		EndAt:           0,
+		EndAt:           2000000000,
 		CreateAt:        0,
 		Seats:           0,
 		IsFreeTrial:     "true",