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/scheme.go

@@ -33,7 +33,7 @@ func createScheme(c *Context, w http.ResponseWriter, r *http.Request) {
 	defer c.LogAuditRec(auditRec)
 	auditRec.AddMeta("scheme", scheme)
 
-	if c.App.Srv().License() == nil || !*c.App.Srv().License().Features.CustomPermissionsSchemes {
+	if c.App.Channels().License() == nil || !*c.App.Channels().License().Features.CustomPermissionsSchemes {
 		c.Err = model.NewAppError("Api4.CreateScheme", "api.scheme.create_scheme.license.error", nil, "", http.StatusNotImplemented)
 		return
 	}
@@ -190,7 +190,7 @@ func patchScheme(c *Context, w http.ResponseWriter, r *http.Request) {
 	auditRec := c.MakeAuditRecord("patchScheme", audit.Fail)
 	defer c.LogAuditRec(auditRec)
 
-	if c.App.Srv().License() == nil || !*c.App.Srv().License().Features.CustomPermissionsSchemes {
+	if c.App.Channels().License() == nil || !*c.App.Channels().License().Features.CustomPermissionsSchemes {
 		c.Err = model.NewAppError("Api4.PatchScheme", "api.scheme.patch_scheme.license.error", nil, "", http.StatusNotImplemented)
 		return
 	}
@@ -231,7 +231,7 @@ func deleteScheme(c *Context, w http.ResponseWriter, r *http.Request) {
 	auditRec := c.MakeAuditRecord("deleteScheme", audit.Fail)
 	defer c.LogAuditRec(auditRec)
 
-	if c.App.Srv().License() == nil || !*c.App.Srv().License().Features.CustomPermissionsSchemes {
+	if c.App.Channels().License() == nil || !*c.App.Channels().License().Features.CustomPermissionsSchemes {
 		c.Err = model.NewAppError("Api4.DeleteScheme", "api.scheme.delete_scheme.license.error", nil, "", http.StatusNotImplemented)
 		return
 	}