Integrate Uptime Tracker with Transport Discovery

[0pcom]

Proposed solution to this issue:

skycoin/skywire#1758

In summary: multihop routing is crippled by the presence of inactive or dead transports in the transport discovery or a lack of concurrency between the transports registered on the visor and thoose in the transport discovery.

Instead of making the transport discovery reliant on the uptime tracker data, a better solution would be to combine the two into a single service and eliminate the uptime tracker as a separate service.

• re-registration interval for transports in TPD
• report bandwidth and latency for transports to TPD upon re-registration or removal of transport