Add logic to node class to block txs until BC is init

[peytonlundquist]

Description

Add logic for full nodes to reject transactions if they received any before initialized.

Nodes will encounter a critical error if they receive a TX before the BC is initialized. They should not fail.

They could store the TX in the mempool and wait till BC is init to add, or they could reject the tx

Acceptance Criteria

The BC network runs, a client submits TX before they print their chains, it does not break the network