[Draft] Ownable 2 step

[ggonzalez94]

Resolves #290

• Introduce a new Ownable2Step contract
• Make onlyOwner() internal in Ownable and implement MethodError to be able to use the error in our new contract(we've already seen we will need it for others)

PR Checklist

• Unit Tests
• e2e Tests
• Documentation

[netlify]

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[codecov]

Codecov Report

Attention: Patch coverage is 88.23529% with 20 lines in your changes missing coverage. Please review.

Project coverage is 82.2%. Comparing base (46eabf0) to head (e00fbc3).

Files with missing lines	Patch %	Lines
contracts/src/access/ownable_two_step.rs	89.1%	17 Missing ⚠️
contracts/src/access/ownable.rs	76.9%	3 Missing ⚠️

Additional details and impacted files

Files with missing lines	Coverage Δ
contracts/src/access/ownable.rs	74.5% <76.9%> (-2.0%)	⬇️
contracts/src/access/ownable_two_step.rs	89.1% <89.1%> (ø)