MM-47228 - restrict guest invitation flow if subscription plan does n… (#21195)

* MM-47228 - restrict guest invitation flow if subscription plan does not support it

* fix i18n texts and add unit test

* test the scenario where guest invites are blocked by subscription

* cover the success scenarios for cloud free trial and paid subscription

* fix go vet

* use the cloud prefix for the sku

* fix unit tests

* check the licence value to determine if the guest accounts are enabled

* remove unnecessary changes for getting the subscription information

* restrict user demotion if guestAccounts is not available in license

Co-authored-by: Pablo Velez Vidal <pablo.velez@mattermost.com>

api4/team.go

@@ -1462,12 +1462,12 @@ func inviteUsersToTeam(c *Context, w http.ResponseWriter, r *http.Request) {
 func inviteGuestsToChannels(c *Context, w http.ResponseWriter, r *http.Request) {
 	graceful := r.URL.Query().Get("graceful") != ""
 	if c.App.Channels().License() == nil {
-		c.Err = model.NewAppError("Api4.InviteGuestsToChannels", "api.team.invate_guests_to_channels.license.error", nil, "", http.StatusNotImplemented)
+		c.Err = model.NewAppError("Api4.InviteGuestsToChannels", "api.team.invite_guests_to_channels.license.error", nil, "", http.StatusNotImplemented)
 		return
 	}
 
 	if !*c.App.Config().GuestAccountsSettings.Enable {
-		c.Err = model.NewAppError("Api4.InviteGuestsToChannels", "api.team.invate_guests_to_channels.disabled.error", nil, "", http.StatusNotImplemented)
+		c.Err = model.NewAppError("Api4.InviteGuestsToChannels", "api.team.invite_guests_to_channels.disabled.error", nil, "", http.StatusNotImplemented)
 		return
 	}
 
@@ -1485,6 +1485,13 @@ func inviteGuestsToChannels(c *Context, w http.ResponseWriter, r *http.Request)
 		return
 	}
 
+	guestEnabled := c.App.Channels().License() != nil && *c.App.Channels().License().Features.GuestAccounts
+
+	if !guestEnabled {
+		c.Err = model.NewAppError("Api4.InviteGuestsToChannels", "api.team.invite_guests_to_channels.disabled.error", nil, "", http.StatusForbidden)
+		return
+	}
+
 	var guestsInvite model.GuestsInvite
 	if err := json.NewDecoder(r.Body).Decode(&guestsInvite); err != nil {
 		c.Err = model.NewAppError("Api4.inviteGuestsToChannels", "api.team.invite_guests_to_channels.invalid_body.app_error", nil, "", http.StatusBadRequest).Wrap(err)