MM-40817: Use license interface in Channels (#19678)

* MM-40817: Use license interface in Channels

https://mattermost.atlassian.net/browse/MM-40817

```release-note
NONE
```

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

api4/channel.go

@@ -1792,7 +1792,7 @@ func updateChannelScheme(c *Context, w http.ResponseWriter, r *http.Request) {
 	defer c.LogAuditRec(auditRec)
 	auditRec.AddMeta("new_scheme_id", *schemeID)
 
-	if c.App.Srv().License() == nil {
+	if c.App.Channels().License() == nil {
 		c.Err = model.NewAppError("Api4.UpdateChannelScheme", "api.channel.update_channel_scheme.license.error", nil, "", http.StatusNotImplemented)
 		return
 	}
@@ -1886,7 +1886,7 @@ func channelMembersMinusGroupMembers(c *Context, w http.ResponseWriter, r *http.
 }
 
 func channelMemberCountsByGroup(c *Context, w http.ResponseWriter, r *http.Request) {
-	if c.App.Srv().License() == nil {
+	if c.App.Channels().License() == nil {
 		c.Err = model.NewAppError("Api4.channelMemberCountsByGroup", "api.channel.channel_member_counts_by_group.license.error", nil, "", http.StatusNotImplemented)
 		return
 	}
@@ -1919,7 +1919,7 @@ func channelMemberCountsByGroup(c *Context, w http.ResponseWriter, r *http.Reque
 }
 
 func getChannelModerations(c *Context, w http.ResponseWriter, r *http.Request) {
-	if c.App.Srv().License() == nil {
+	if c.App.Channels().License() == nil {
 		c.Err = model.NewAppError("Api4.GetChannelModerations", "api.channel.get_channel_moderations.license.error", nil, "", http.StatusNotImplemented)
 		return
 	}
@@ -1956,7 +1956,7 @@ func getChannelModerations(c *Context, w http.ResponseWriter, r *http.Request) {
 }
 
 func patchChannelModerations(c *Context, w http.ResponseWriter, r *http.Request) {
-	if c.App.Srv().License() == nil {
+	if c.App.Channels().License() == nil {
 		c.Err = model.NewAppError("Api4.patchChannelModerations", "api.channel.patch_channel_moderations.license.error", nil, "", http.StatusNotImplemented)
 		return
 	}