## Description
Expose p2p functions for use in the sdk.
These functions could also be copied over to the sdk. I dont have a preference of which is better.
This PR make some tweaks to backfill after running e2e tests:
- Separates sync and backfill as two distinct processes that the node calls. The reason is because if sync fails then the node should fail but if backfill fails it is still possible to proceed.
- Removes peers who don't have the block at a height from the local peer list. As the process goes backwards if a node doesn't have a block at a height they're likely pruning blocks and thus they won't have any prior ones either.
- Sleep when we've run out of peers, then try again.
I believe that this, in my testing seems to help the e2e state-sync
tests complete more reliably, by fixing some potential, range-related
slice building, as well as the way the test app hashes snapshots.
Additionally, and I'm not sure if we want to do this, but I added this
hook to the reactor that re-sends the request for snapshots during the
retry. This helps in tests prevent systems from getting stuck, but I
think in reality, it might create more traffic, and operators would
just restart a state-syncing node to get a similar effect.
* test/fuzz: fix rpc, secret_connection and pex tests
- ignore empty data in rpc
- provide correct IP in pex
- spawn a goroutine for Write and do multiple Read(s)
* test/fuzz: fix init in pex test
* test/fuzz: assign NewServeMux to global var
* test/fuzz: only try to Unmarshal if blob is not empty
* run fuzz tests for PRs which modify fuzz tests themselves
* test/fuzz: move MakeSwitch into init