BIP352: PSBT support

This update is based on the work available at this gist by RubenSomsen, which provides the necessary technical insight and background for integrating the DLEQ proof into the BIP. The inclusion of the DLEQ proof represents a critical step forward in the development of the BIP, indicating a focus on cryptographic rigor and the proposal’s alignment with current best practices in the field.

This enhancement not only strengthens the proposal by incorporating advanced cryptographic techniques but also signals the BIP authors' commitment to maintaining high security and reliability standards. By drawing from established research and developments such as the one provided by RubenSomsen, the BIP demonstrates an ongoing effort to incorporate peer-reviewed innovations that could potentially set new benchmarks within the domain it seeks to contribute to.