fix: adjust system contracts directories

[cfsdes]

What 💻

• The hardcoded path from system_contracts.rs was updated from etc/system-contracts to contracts/system-contracts.
• The hardcoded path used in fee_estimate_impersonating_contracts() function was also updated

Why ✋

The system_contracts.rs was reading some artifacts from the etc/ directory.

However, when system contracts (such as era contracts) are compiled, their artifacts are usually stored in the same path as their contracts. Therefore, to avoid errors, the hardcoded path was updated from etc/system-contracts to contracts/system-contracts.

Also, the fee_estimate_impersonating_contracts() function was using an invalid directory, so it was also updated.

Evidence 📷

The image below is an evidence of the era_test_node being executed correctly with era-contracts.

PS: In order for the tool to work properly, the system-contracts/ directory was moved to inside the contracts/ directory.

[dutterbutter]

@cfsdes can you please address the failed lint job.

[cfsdes]

Sure @dutterbutter. Now it should be working well :)

[MexicanAce]

LGTM