Add certificates settings for medusa encryption

[rexbut]

What this PR does:
This PR enhances the K8ssandra Operator by adding customizable TLS certificate settings for Medusa client-side encryption. Specifically, it introduces a new certificatesSettings configuration option, which allows users to specify custom names for the CA certificate, client certificate, and client private key within the Secret's data field.

This enhancement ensures compatibility with CertManager by allowing users to map the standard CertManager keys (ca.crt, tls.crt, tls.key) to the Medusa configuration:

"medusa" = {
  "certificatesSettings" = {
    "certfile" = "ca.crt"
    "usercert" = "tls.crt"
    "userkey"  = "tls.key"
  }
}

Which issue(s) this PR fixes:
Fixes #

Checklist

• Changes manually tested
• Automated Tests added/updated
• Documentation added/updated
• CHANGELOG.md updated (not required for documentation PRs)
• CLA Signed: DataStax CLA

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
0.0% Duplication on New Code

See analysis details on SonarCloud

[github-actions]

No linked issues found. Please add the corresponding issues in the pull request description.
Use GitHub automation to close the issue when a PR is merged