Generate api.md for Java module

Add `--renderer=markdown` option to https://github.com/Azure/azure-sdk-tools/tree/main/src/java/apiview-java-processor

- https://github.com/Azure/azure-sdk-tools/pull/16809

---

Integration

- [ ] integrate into SDK Generation pipeline
- [ ] command to generate `api.md` when user does not use the pipeline (this is what Python does -- another alternative is to have agent on PR to regen the `api.md` and commit, if not match)

---

Question

- How to build the apiview-java-processor, given it currently in the tools repo? Should we move it into SDK repo? Or upload the build to devfeed?