NDEV-2514: Refactor get_config module

[andreisilviudragnea]

• Moved all code related to retrieving chain configuration into get_config module.
• Added more object orientation, by adding the program_id: Pubkey to ConfigSimulator enum variants and converting most functions to methods on ConfigSimulator enum.
• Isolated ProgramTestContext retrieval from PROGRAM_TEST_CONTEXT static variable inside program_test_context function, so it can be easier changed to a new ProgramTestContext for each request model during testing.
• A few renames to make it clear the difference between simulate_evm_instruction vs simulate_solana_instruction.
• Removed some unused code.

[anton-lisanin]

@s-medvedev please check if this conflicts with your interoperability plans.

[Deniskore]

I have no objections 👍🏼