Add extensive test cases for possible "invalid" blocks

[janniks]

Not all possible reasons for not being valid are tested currently. e.g.

stacks-core/testnet/stacks-node/src/tests/signer/v0.rs

Line 39 in 2be69cb

use stacks::net::api::postblock_proposal::{ValidateRejectCode, TEST_VALIDATE_STALL};

Create more tests.

Possible errors for ValidateRejectCode:

• BadBlockHash = 0 -> build on top of this function
• BadTransaction = 1 -> build on top of the same validate function as BadBlockHash
• InvalidBlock = 2 - unit test and integration test
• ChainstateError = 3 - integration test
• UnknownParent = 4 - integration test
• NonCanonicalTenure = 5 - integration test
• NoSuchTenure = 6 -> same integration test as NonCanonicalTenure

All functions that aren't yet tested are part of theimpl NakamotoBlockProposal.

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To do: Construct bad block proposal and submit to the signers. See how the signers deal with it.