This enables the following linters
- typecheck
- unused
- staticcheck
- bidichk
- durationcheck
- exportloopref
- gosec
WIth a few exceptions.
- We use a deprecated protobuf in trezor. I didn't want to mess with that, since I cannot meaningfully test any changes there.
- The deprecated TypeMux is used in a few places still, so the warning for it is silenced for now.
- Using string type in context.WithValue is apparently wrong, one should use a custom type, to prevent collisions between different places in the hierarchy of callers. That should be fixed at some point, but may require some attention.
- The warnings for using weak random generator are squashed, since we use a lot of random without need for cryptographic guarantees.
This PR implements the first one of the "lespay" UDP queries which
is already useful in itself: the capacity query. The server pool is making
use of this query by doing a cheap UDP query to determine whether it is
worth starting the more expensive TCP connection process.
* les: move serverPool to les/vflux/client
* les: add metrics
* les: moved ValueTracker inside ServerPool
* les: protect against node registration before server pool is started
* les/vflux/client: fixed tests
* les: make peer registration safe
