Avoid byte array copies when verifying signatures

`EcdsaSecp256k1VerificationProvider.handleItem()` and `Ed25519VerificationProvider.handleItem()` convert `Bytes` provided in `TransactionSignature` to byte arrays required by native signature verification libraries.
To avoid byte array copies, an approach similar to one used in `CryptoStatic.verifySignature()` should be considered: delegate calling actual signature verification to Bytes preserving its immutability and avoiding exposing its internal `byte[]`.
See also #18146.

Start with EcdsaSecp256k1VerificationProvider.handleItem() and Ed25519VerificationProvider.handleItem(), then compare their byte-array conversion with CryptoStatic.verifySignature(). The work is done when signature verification delegates through Bytes without exposing its internal byte[] or making unnecessary copies, while preserving existing verification behavior.

Written by the indexing model from the issue text.