Support OCI GenAI embedding model

[anders-swanson]

Expected Behavior

Support Oracle Cloud Infrastructure (OCI) GenAI Embedding models

Current Behavior

No implementation exists

Context

Spring AI has support for Oracle vector database, but is missing some pieces around gen AI. I'd like to fill in those gaps with the relevant implementations.

[anders-swanson]

I've created a PR for the embedding model here, that should resolve this issue: #1254