feat: track server last sent/received (#728)

### Description

- Track `last_sent` / `last_received` for debugging stuck connections
- Remove contention from server stats mutex - one mutex per connection
for stats instead
- time stats are now subms precision (e.g. 32.342ms) including in admin
DB and Prometheus

fix: prepared statements eviction CPU churn (#712)

When prepared statements were frequently evicted, the algorithm that was
calculating the memory usage for the prepared statement data structure
iterated over every single statement in the cache. This was effectively
O(n^2) in the worst case, and it was burning CPU to provide only an
approximation.

This change uses a simpler algorithm to calculate memory usage that
doesn't have to walk the entire data structure.

test: add NotificationResponse regression test (#706)

To prevent parsing errors for that message.

v0.1.23 (#704)

v0.1.22 (#700)

v0.1.21 (#694)

chore: add param reset test & tag release (#683)

- chore: add `RESET` test for #682
- chore: tag release