add various key generation to keystore

[Tofel]

PRODCRE-1800, PRODCRE-1801, PRODCRE-1802, PRODCRE-1803, PRODCRE-1825

added generation of following keys to the keystore:

• evm
• solana
• p2p
• dkg
• workflow key

[Copilot]

Pull request overview

This PR adds support for DKG (Distributed Key Generation) and Workflow keys to the corekeys keystore. The implementation enables generation, encryption, and decryption of these key types compatible with the core node.

Changes:

• Added DKG key generation and import functionality with ECDH P256 encryption
• Added Workflow key generation and import functionality with X25519 encryption
• Implemented comprehensive test coverage for both key types including round-trip, wrong password, and invalid format scenarios

Reviewed changes

Copilot reviewed 4 out of 4 changed files in this pull request and generated no comments.

File	Description
keystore/corekeys/dkg.go	Implements DKG key generation, encryption, and decryption using ECDH P256
keystore/corekeys/dkg_test.go	Test suite for DKG key operations including round-trip, authentication, and validation
keystore/corekeys/workflowkey.go	Implements Workflow key generation, encryption, and decryption using X25519
keystore/corekeys/workflowkey_test.go	Test suite for Workflow key operations including round-trip, authentication, and validation

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[github-actions]

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[github-actions]

✅ API Diff Results - No breaking changes

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[Copilot]

Pull request overview

Copilot reviewed 12 out of 12 changed files in this pull request and generated no new comments.

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[pavel-raykov]

PRODCRE-1800,
@cedric-cordenier

Sorry, on a high level I first want to understand the proposed solution for https://smartcontract-it.atlassian.net/browse/PRODCRE-1747

The keystore library https://github.com/smartcontractkit/chainlink-common/tree/main/keystore is not supposed to give private keys. In particular, the intended use case is to wrap existing interface around the keystore to call the underlying sign/encrypt functions. This is an example - https://github.com/smartcontractkit/chainlink-common/tree/main/keystore/ragep2p, notice that we don't export ed25519 private key, but we wrap the keystore to provide the Sign function needed to implement ragetypes.PeerKeyring.

This PR (and its ancestor #1793) looks like a very weird way of generating a key using this library: 1. you generate a key. 2 encrypt it. 3. decrypt it to raw bytes, where the last step works just because you "guessed" the decryption function (otherwise you won't be able to read the private keys and you are only able to import them). So, currently using the keystore library in such a way looks very weird.

If indeed you truly need to read private keys, then we can just make a standalone API for key generation without the need for serialization/deserialization and other excessive steps.