Helm: Enabling passing multi-line strings for custom.configuration.discoveryDetails parameter in Helm values.

[karok2m]

What this PR does / why we need it:

This PR enables passing multi-line strings such as the one bellow to custom.configuration.discoveryDetails parameter in deployment\helm\values.yaml file of the Helm chart.

Ability to provide multi-line strings will enable passing well-structured and complex discovery requests to custom discovery handlers. This will also align configuration of custom discovery handler with the configuration of the existing discovery handlers (debugEcho, onvif, opcua and others) which support more structured hierarchical configuration for discoveryDetails.

custom:
  configuration:
    enabled: true
    name: akri-opcua-asset
    discoveryHandlerName: opcua-asset
    discoveryDetails: |
      discoveryMethod:
        asset:
          endpointUrl: "opc.tcp://umati.akri.svc.cluster.local:4840/"

Special notes for your reviewer:

The changes are only on the Helm chart side. No changes were added to the Rust code, so cargo-related checkboxes below are irrelevant.

If applicable:

• this PR has an associated PR with documentation in akri-docs
• this PR contains unit tests
• added code adheres to standard Rust formatting (cargo fmt)
• code builds properly (cargo build)
• code is free of common mistakes (cargo clippy)
• all Akri tests succeed (cargo test)
• inline documentation builds (cargo doc)
• all commits pass the DCO bot check by being signed off -- see the failing DCO check for instructions on how to retroactively sign commits

[kate-goldenring]

/version patch

[kate-goldenring]

Thanks @karok2m!