Port PR from PBC-Java: Add api-key authorization to external UUID handling

[cross-repo-issue-creation]

A PR was merged over on PBC-Java

• Add api-key authorization to external UUID handling prebid-cache-java#156
• timestamp: 2025-02-20T00:32:34Z

[bretg]

New PBC YAML config options

• api.external-UUID-secured: when 'true', adds an additional security API check for cache.allow-external-UUID property. Which means that writes that contain a key can be only enabled for trusted hosts. Default is 'false'.
• api.cache-write-secured: when 'true' will only allow cache writes for trusted hosts. Default is 'false'.

Authentication is done using the configured API key.

Related metric

• pbc.err.rejectedExternalId: this is incremented when the client specifies the UUID key but is not allowed.