feat: (A-302) add reloadKeystore admin RPC endpoint

[danielntmd]

• Allow node operators to update coinbase, fee recipient, and validator attester keys without restarting by re-reading keystore files from disk.

What is updated on reload:

• Validator attester keys (add, remove, or replace)
• Coinbase and fee recipient per validator
• Publisher-to-validator mapping in the sequencer publisher factory
• Slasher "don't-slash-self" list
• HA signer preserved (PostgreSQL connection pool reused)

What is NOT updated (requires node restart):

• L1 publisher signers (funded accounts that send L1 transactions)
• Prover keys
• HA signer connections

Validation is performed before any state mutation:

• Keystore files are loaded, merged, and validated
• New validators must use a publisher key already initialized at startup;
  reload is rejected with a clear error if a publisher key is unknown
• If any validation fails, the old keystore remains in effect

Tests:

• unit tests, error paths, e2e, etc

[AztecBot]

Flakey Tests

🤖 says: This CI run detected 1 tests that failed, but were tolerated due to a .test_patterns.yml entry.

\033FLAKED\033 (8;;http://ci.aztec-labs.com/79f274067b914d63�79f274067b914d638;;�): yarn-project/scripts/run_test.sh p2p/src/client/test/p2p_client.integration_message_propagation.test.ts (22s) (code: 1) group:e2e-p2p-epoch-flakes