Use testnet blocks in the unit tests

[teor2345]

At the moment, zebra-test only has mainnet test vectors.

Let's add some testnet blocks to zebra-test, and use them in the tests:

• Add testnet blocks to zebra-test
• Update zebra-chain tests
• Update zebra-state tests
• Update zebra-consensus tests

Let's use a different PR for each crate where we update the tests.

It might be helpful to have utility functions that:

• return the genesis block data, based on the network,
• return all the test vector block data for a network
• return all the test vector block data, regardless of the network

It might also be helpful to re-write some of our tests to take a Network enum parameter.

[teor2345]

@oxarbitrage you might be interested in doing this ticket.

[oxarbitrage]

Will take it, thanks @teor2345

[teor2345]

We've added the testnet blocks, but we still need to use them in more tests.

[teor2345]

No-one is working on this ticket at the moment

[teor2345]

These tests either got fixed, or they are obsolete.