improve openapi docs, documentaing returned 
null instead of empty array

The following extended metrics information are exposed through
the debug API:
- last seen timestamp - updated every time when the peer
connects/disconnects
- connection total duration - sums of the duration of the sessions
  (in seconds)
- session connection retry count - number of attempts to create
  a new connection
- session connection duration - duration (in seconds) of last or
  current (if in progress) session
- session connection direction - specifies whether the connection is
  outbound or inbound

The POST pinning endpoint returns now 404 on non-existing chunks
instead of 500.

* feat: reupload local content

* feat: reupload. address comments

- Don't account for failed attempts during retries
- LRU Cache to remember failed traces and select better peers
- Metrics

reuses localstore SubscribePull results for peers that request the same interval at the same time

Decreases the time for building the topology by doing the connection attempts to peers concurrently.

cmd: explicitly discard returned values from winlogs

pushsync: add unsigned receipts to verify in-neighborhood replication peers accepted chunk and can be accounted for

This quick-fix prevents the mantaray manifest IterateAddresses method
walker to fail when it encounters an empty address, otherwise, the unpin
traversal operation for the manifest fails.