Function get_ecdsa_public_key

Retrieves the ECDSA public key for the given derivation path from the ECDSA API. This function checks the local in-memory cache first. If no cached key exists, it queries the ECDSA API for the public key at the given derivation path and stores the result in the cache.

(ctx: &BitcoinContext, derivation_path: Vec<Vec<u8>>)