PLT-7633 (E20) Add session idle timeout config setting (#7524)

* Add session idle timeout config setting

* Modify config setting name to SessionIdleTimeoutInMinutes

* Small re-org of if statement

* Merge with latest master

api4/context.go

@@ -157,6 +157,7 @@ func (h handler) ServeHTTP(w http.ResponseWriter, r *http.Request) {
 			c.Err = model.NewAppError("ServeHTTP", "api.context.token_provided.app_error", nil, "token="+token, http.StatusUnauthorized)
 		} else {
 			c.Session = *session
+			c.App.UpdateLastActivityAtIfNeeded(*session)
 		}
 	}