Add dedicated OData API support (extract & publish)

## Summary

apiops-cli currently handles OData APIs via the generic OpenAPI fallback path, which does not capture OData-specific artifacts. This issue tracks adding first-class OData support to both the extractor and publisher.

## Background

Azure API Management added OData API support, but tooling across the ecosystem has lagged behind (see [Azure/apiops#419](https://github.com/Azure/apiops/issues/419)). Users report that entity sets and functions are lost when extracting/publishing OData APIs.

## Current behavior

- **Extractor** (`api-extractor.ts`): No special-case handling for `odata` API type — it falls through to the generic `openapi-link` export, which misses OData-specific resources.
- **Publisher** (`api-publisher.ts`): Recognizes `odata` as a valid `apiType` string but has no OData-specific import format or schema handling.
- **APIM Client** (`apim-client.ts`): `getExportFormat()` returns `'openapi-link'` for OData via the `default` case — no dedicated export format.

## What needs to change

1. **Extract**: Add OData-specific handling in `api-extractor.ts` to export CSDL schemas, entity sets, and functions via the appropriate APIM export format.
2. **APIM Client**: Add an `'odata'` case to `getExportFormat()` returning the correct APIM export format for OData APIs (investigate whether APIM supports a dedicated OData/CSDL export link).
3. **Publish**: Add OData-specific import format handling in `getImportFormat()` so that CSDL schemas and entity sets are correctly imported on publish.
4. **Tests**: Add unit/integration tests covering OData extract and publish flows.

## Related

- [Azure/apiops#419](https://github.com/Azure/apiops/issues/419) — original feature request in the apiops toolkit repo

Start in api-extractor.ts, api-publisher.ts, and apim-client.ts, tracing the existing apiType handling and getExportFormat()/getImportFormat() paths. Check the APIM API format documentation or existing client behavior to confirm the OData/CSDL export and import formats. Done means OData entity sets and functions survive extract and publish, with unit or integration tests covering both flows.

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