[Bug]: When enabling/diabling library watcher, change does not take effect until server restart

[mikiher]

Describe the issue

When you enable or disable folder watcher for a library, the change doesn't acrually happen until server restart.

We should at least let the user know they should restart the server for the change to take effect.

Steps to reproduce the issue

1. Enable or disable a library's folder watcher through the library setting "Enable folder watcher for library".
2. Save.

The server now requires a restart for the setting to take effect (if disabled, watcher still listens and acts on changes. If enabled, watcher is not set up until server restart).

Audiobookshelf version

v2.8.1

How are you running audiobookshelf?

Built from source

[advplyr]

Fixed in v2.9.0