fix: allow accounts to be nullable in `readContract` and add `sim_getTransactionsForAddress` method

[AgustinRamiroDiaz]

What

• fixed typo
• used constant instead of hardcoded string
• allowed accounts to be nullable in readContract
• added sim_getTransactionsForAddress method

Why

• continuous improvements
• needed the features / fixes

Testing done

Added unit tests

Decisions made

Checks

• [x] I have tested this code
• [x] I have reviewed my own PR
• [ ] I have created an issue for this PR
• [x] I have set a descriptive PR title compliant with conventional commits

Reviewing tips

User facing release notes

[AgustinRamiroDiaz]

@cristiam86 @denishacquin do you know how to impose typescript checks in the tests? I'm being able to just test logic, but not typing

[cristiam86]

@cristiam86 @denishacquin do you know how to impose typescript checks in the tests? I'm being able to just test logic, but not typing

I think that typing should be static, not tested. Do you have a concrete example?

[AgustinRamiroDiaz]

@cristiam86 I've managed to add tests to verify typing

[AgustinRamiroDiaz]

I've also fixed all eslint errors so test pass