Fix/audit

[dvilelaf]

Proposed changes

• Implements the required audit changes: the main change is that the backend now does not blindly trust the frontend, so users need to sign messages in order to provide proof about their intentions of creating or voting for proposals.
• Since the preprocessing and postprocessing "preparations" for each tool now need to make contract and ledger api calls, I had to turn every one of them into generators.

Fixes

n/a

Types of changes

What types of changes does your code introduce? (A breaking change is a fix or feature that would cause existing functionality and APIs to not work as expected.)
Put an x in the box that applies

• Non-breaking fix (non-breaking change which fixes an issue)
• Breaking fix (breaking change which fixes an issue)
• Non-breaking feature (non-breaking change which adds functionality)
• Breaking feature (breaking change which adds functionality)
• Refactor (non-breaking change which changes implementation)
• Messy (mixture of the above - requires explanation!)

Checklist

Put an x in the boxes that apply.

• I have read the CONTRIBUTING doc
• I am making a pull request against the main branch (left side). Also you should start your branch off our main.
• Lint and unit tests pass locally with my changes
• I have added tests that prove my fix is effective or that my feature works
• I have locally run services that could be impacted and they do not present failures derived from my changes

Further comments

n/a