Make "Reload config" button actually reload the config file

[shouya]

Currently, the config file is automatically reload through the watcher implementation. However, in certain types of deployments, changes to the config file is not always detected using the watcher. In that case, instead of running the watcher in polling mode, which is wasteful and has high latency, it would be ideal the change can be manually signaled by the user.

On the other hand, the "Reload config" button only reload the front-end. This means the changes not picked up by the backend (i.e. the watcher) is not going to reflect on the front-end. The title of the button is a bit misleading because it does not really request the backend to reload of the config.

So the planned change goes like this: First implement a synchronous reload subroutine in the watcher that can be triggered manually, next point the "Reload config" button to this new reload subroutine. Finally, ensure the reloaded config is reflected on the webui.