Get pending nonce

[mvandeberg]

Brief description

When submitting a transaction to chain, chain first checks for a pending nonce from the mempool and uses it as the account nonce if it exists. This allows a user to queue sequential nonces prior to earlier transactions being included in blocks.

Checklist

• I have built this pull request locally
• I have ran the unit tests locally
• I have manually tested this pull request
• I have reviewed my pull request
• I have added any relevant tests

Demonstration

❯ ./run.sh pending_nonce                               
~/dev/koinos-integration-tests/tests/pending_nonce ~/dev/koinos-integration-tests
[+] Running 6/6
 ✔ Network pending_nonce_default          Created                                                                                                                                                                                                     0.1s 
 ✔ Container pending_nonce-amqp-1         Started                                                                                                                                                                                                     0.2s 
 ✔ Container pending_nonce-chain-1        Started                                                                                                                                                                                                     0.3s 
 ✔ Container pending_nonce-block_store-1  Started                                                                                                                                                                                                     0.5s 
 ✔ Container pending_nonce-jsonrpc-1      Started                                                                                                                                                                                                     0.5s 
 ✔ Container pending_nonce-mempool-1      Started                                                                                                                                                                                                     0.5s 
=== RUN   TestPublishTransaction
    integration.go:699: Waiting 1s for chain to be ready...
    integration.go:699: Waiting 2s for chain to be ready...
    integration.go:699: Waiting 4s for chain to be ready...
--- PASS: TestPublishTransaction (7.04s)
PASS
ok      koinos-integration-tests/tests/pending_nonce    7.056s
[+] Running 6/6
 ✔ Container pending_nonce-jsonrpc-1      Removed                                                                                                                                                                                                     0.2s 
 ✔ Container pending_nonce-mempool-1      Removed                                                                                                                                                                                                     0.3s 
 ✔ Container pending_nonce-block_store-1  Removed                                                                                                                                                                                                     0.1s 
 ✔ Container pending_nonce-chain-1        Removed                                                                                                                                                                                                     0.3s 
 ✔ Container pending_nonce-amqp-1         Removed                                                                                                                                                                                                     1.2s 
 ✔ Network pending_nonce_default          Removed                                                                                                                                                                                                     0.2s 
~/dev/koinos-integration-tests