Add keystore service to standardcapabilities delegate

[vreff]

• Adds a multi-account signer to every standardcapabilities job.
• Signer should use the P2P key if available, otherwise it will contain an empty list of signers.
• Requires: https://github.com/smartcontractkit/chainlink-common/pull/1269

[cl-sonarqube-production[bot]]

Quality Gate failed

Failed conditions
B Maintainability Rating on New Code (required ≥ A)
5.19% Technical Debt Ratio on New Code (required ≤ 4%)

See analysis details on SonarQube

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