Migrate immutable values for test contract

[popzxc]

Component

Forge

Describe the bug

#1078 introduced a fix for test contract not being available in EraVM context.
However, it has a bug: immutable values are not migrated for it.

To reproduce, remote the #[ignore] attribute on the test_zk_can_invoke_test_contract_with_immutables test added in the abovementioned PR -- it will fail.

The exact approach to fix the bug is not clear. I see two options:

1. Try to deduce the slots for ImmutableSimulator based on deployed bytecode and immutable references. Not sure if it's possible: zksolc assigns slots for the simulator based on the order in which values are assigned, not declared, and AFAIU we can't get this information easily.
2. Try to deploy the contract in the EraVM context and check which slots will be set. This feels error-prone, since a lot of factors can cause different values for immutables between EraVM and EVM. If we're going to go this way, I would probably suggest to add a safety check: after getting immutables for EraVM contract, extract values from deployed EVM contract and ensure that set(eravm_immutable_values) == set(evm_immutable_values).

[nbaztec]

Upon further investigation:

• It is possible to retrieve the number of immutables m from solc artifacts.
• It is possible to calculate all immutable storage keys 32 * n indices apart.

However the following requisites are still missing:

• An approach to store immutable value per deployed contract that can be used during storage migrations to populate StoraveValue for each computed immutable address.
• An approach to detect all replaced immutable values in a deployed contract bytecode (for value extraction)
• An approach to map them to their correct and corresponding equivalents in StorageKeys.
• Fix a bug in compilation to allow requesting custom OutputSelections - (e.g. ir) that is required for computing exact StorageKeys indices corresponding to solc equivalents.