Add function to retrieve the master key fingerprint

[miketlk]

Description

Currently, applications that need the master key fingerprint must derive the master pubkey, which requires setting an empty derivation path in the load parameters and ledger-app-database. A dedicated master key fingerprint function would allow apps to avoid master pubkey derivation and reduce the need for unrestricted path access, making them more complaint with the current security requirements.

Proposed Solution

Introduce a function in the SDK that directly returns the master key fingerprint, supporting more secure and specific path configurations in applications that require this data. Currently, this feature is needed for the new Liquid Network app, using the same format of master key fingerprint as Bitcoin. However, it's worth considering an extendable API, potentially supporting other hashing methods if they would be asked for some other apps.