test: starkli declare workflow in test

[ICavlek]

Create integration test with mock starknet node where beerus requests are going to simulate starkli declare workflow function calls:

• starknet_chainId
• starknet_getClass
• starknet_chainId
• starknet_getNonce
• starknet_specVersion
• starknet_estimateFee
• starknet_addDeclareTransaction

[ICavlek]

It has been decided that mock tests are redundant.

[sergey-melnychuk]

Mocks may be not as redundant as I thought actually. For the external contributor flow, GitHub doesn't propagate repository secrets (in order not to leak them, this is expected). But in practice it means that no PR from external contributors can run integration tests properly.

In such case mock tests might be the way to go - hermetic check of request/response invariants.