[Security]: Avoid PrivateKey.cpp abuse resistance

[satoshiotomakan]

Describe the bug

Consider inserting the curve as a parameter to the private key and its storage. In addition, the Trust Wallet team should rigorously enforce that private keys cannot be accidentally used to generate signatures on multiple curves or signature schemes. To achieve this, the method sign’s implementation should either check that the parameter curve matches the curve parameter of the private key, or simply drop the parameter so that a private key is always used in tandem with the intended curve. The method signAsDER currently uses K-256 implicitly, which should check that the private key corresponds to this curve. Despite the lack of an associated flaw in the code at present, this approach should be installed due to the propensity for algorithm confusion attacks in the modern era.