GOLD-211: ECDSA Multi-sig feature

[arhamj]

Task: https://linear.app/shm/issue/GOLD-211/

• Added config to hold a mapping of allowed keys for multi-sig
• Adding and unifying multi-sig related flags.
• Adding support to accept a verifyMultiSigs method implementation from the app layer. To let curve specific logic to reside on the app layer.
• Updated and renamed middleware to use the above.
• Updated /df endpoint to use this middleware by default

[github-actions[bot]]

PR Reviewer Guide 🔍

⏱️ Estimated effort to review: 4 🔵🔵🔵🔵⚪

🧪 No relevant tests

🔒 No security concerns identified

⚡ Key issues to review Configuration Consistency The PR introduces new configurations for multi-signature keys and requirements (`multisigKeys`, `minMultiSigRequiredForEndpoints`, `minMultiSigRequiredForGlobalTxs`). It's crucial to ensure that these new settings are consistent with the existing system configurations and that they are being used correctly throughout the application. Security Validation The new methods `ensureMultisigKeySecurity` and `verifyMultiSigs` are added to handle multi-signature validation. It's important to thoroughly review these methods to ensure they correctly implement the intended security checks without introducing vulnerabilities. Middleware Authentication Changes in middleware to support multi-signature authentication (`handleDebugMultiSigAuth`) need careful examination to ensure that they correctly authenticate requests and handle errors without allowing unauthorized access or information disclosure. Method Implementation The implementation of `verifyMultiSigs` in the `Shardus` class should be reviewed for correctness and to ensure it integrates properly with the rest of the application's architecture.