Migrate X-Chain from LevelDB to Firewood and PebbleDB

[joshua-kim]

Why this should be merged

Implements a database migration from the legacy database format into a database format that supports a merkle-ized prefix of state

How this works

Changes db schema

How this was tested

Added a migration unit test + tested state migration on Fuji

[03-20|16:01:06.597] INFO <X Chain> avm/vm.go:173 VM config initialized {"config": {"network":{"max-validator-set-staleness":60000000000,"target-gossip-size":20480,"push-gossip-percent-stake":0.9,"push-gossip-num-validators":100,"push-gossip-num-peers":0,"push-regossip-num-validators":10,"push-regossip-num-peers":0,"push-gossip-discarded-cache-size":16384,"push-gossip-max-regossip-frequency":30000000000,"push-gossip-frequency":500000000,"pull-gossip-poll-size":1,"pull-gossip-frequency":1500000000,"pull-gossip-throttling-period":10000000000,"pull-gossip-throttling-limit":2,"expected-bloom-filter-elements":8192,"expected-bloom-filter-false-positive-probability":0.01,"max-bloom-filter-false-positive-probability":0.05},"index-transactions":false,"index-allow-incomplete":false,"checksums-enabled":false}}
[03-20|16:01:06.597] INFO <X Chain> avm/vm.go:598 fee asset is established {"alias": "AVAX", "assetID": "U8iRqJoiJm8xZHAacmvYyZVwqQx6uDNtQeP3CQ6fcgQk3JqnK"}
[03-20|16:01:06.597] INFO <X Chain> avm/vm.go:257 address transaction indexing is disabled
[03-20|16:01:06.599] INFO <X Chain> snowman/engine.go:96 initializing consensus engine
[03-20|16:01:06.599] INFO <X Chain> bootstrap/bootstrapper.go:320 starting bootstrap
[03-20|16:01:06.601] INFO <X Chain> bootstrap/bootstrapper.go:600 executing transactions
[03-20|16:01:06.601] INFO <X Chain> queue/jobs.go:223 executed operations {"numExecuted": 0}
[03-20|16:01:06.601] INFO <X Chain> bootstrap/bootstrapper.go:612 executing vertices
[03-20|16:01:06.601] INFO <X Chain> queue/jobs.go:223 executed operations {"numExecuted": 0}
[03-20|16:01:06.603] INFO <X Chain> avm/state_migration.go:143 starting state migration
[03-20|16:04:53.784] INFO <X Chain> avm/state_migration.go:321 migration complete
[03-20|16:04:53.790] INFO <X Chain> proposervm/vm.go:209 initialized proposervm {"state": "after fork", "forkHeight": 1, "lastAcceptedHeight": 32356}
[03-20|16:04:53.790] INFO <X Chain> bootstrap/bootstrapper.go:182 starting bootstrapper {"lastAcceptedID": "8o6VfSzPHhjLXwr7FEZDxuVAwXYVCx6dP7vrwLoW9mwYRPZi4", "lastAcceptedHeight": 32356}
[03-20|16:05:42.318] INFO <X Chain> bootstrap/bootstrapper.go:387 starting to fetch blocks {"numKnownBlocks": 99, "numAcceptedBlocks": 1, "numMissingBlocks": 100}
[03-20|16:05:42.857] INFO <X Chain> bootstrap/storage.go:194 executing blocks {"numToExecute": 45}
[03-20|16:05:43.116] INFO <X Chain> bootstrap/storage.go:186 executed blocks {"numExecuted": 45, "numToExecute": 45, "halted": false, "duration": "258.784792ms"}

Need to be documented in RELEASES.md?

Yes

[joshua-kim]

Need to come up with a way to break up this diff. Currently I think that we could break this into:

1. Introducing read-only shared memory
2. firewood package
3. Diff in state