[FEATURE] OHDSIAPI.jl Extension for OMOPCommonDataModel.jl

Context:
In cases where a user does not have a local OMOP CDM database but still wants to access vocabulary or concept-level information (example: concept names, synonyms etc), integrating with OHDSIAPI.jl could offer a lightweight and accessible solution.

Idea:
After a weeking review meeting with @TheCedarPrince, we realized this could be a useful addition to OMOPCommonDataModel.jl. The idea is to create a dedicated extension that leverages OHDSIAPI.jl to fetch OMOP vocabulary and metadata from a remote OHDSI web API server. This would be especially helpful in development, educational, or resource-constrained settings where a full OMOP database is not available.

Why it is useful:
This opens up new workflows for users who:

• Don’t have access to full OMOP vocabularies locally
• Want quick lookups without loading a full database
• Are building educational or lightweight tools that rely on OMOP concepts

Start by reviewing OMOPCommonDataModel.jl and the linked OHDSIAPI.jl project to understand how an extension could access remote OHDSI vocabulary and metadata. The issue does not name files, tests, or an entry point; done would mean a defined extension that supports lightweight concept and vocabulary lookups without a local OMOP database.