fix: double base64 decoding in Filecoin.WalletSign

[LesnyRumcajs]

Summary of changes

Changes introduced in this pull request:

• exposed worker address as part of the api-compare,
• fixed Filecoin.WalletSign endpoint and introduce a conformance test

Reference issue to close (if applicable)

Closes

Other information and links

Change checklist

• I have performed a self-review of my own code,
• I have made corresponding changes to the documentation,
• I have added tests that prove my fix is effective or that my feature works (if possible),
• I have made sure the CHANGELOG is up-to-date. All user-facing changes should be reflected in this document.