Implement new connection verification approach

### Context

Due to WireGuard (and UDP protocol) nature, it's impossible to know whether the connection: actually has been initiated, if it's still "ongoing" or if it's lost, etc.
This confuses users and imposes some difficulties to the IT/Management staff when debugging (if the connection actually works? or do we have ACL problem? etc..).
Also - we have problem with our statistics due to this fact (we estimate the connection inactivity and then decide if the connection is down when there is inactivity for X).

### New feature proposal

But we could introduce an **optional** feature, that our customers would enable like connection verification with gateway ping and gateway communication (about disconnecting, etc) **over only the vpn networks**.

This approach would also provide some possibilities like: inform from the client that it's disconnecting, etc.

This will for sure not resolve all issues like the connection will be lost for some time (changing networks, etc.) or the fact that the Mobile client can't connect in the background with our services non stop... but will be a remedy for some problems.

Any ideas, preferences, comments welcome.