[vector][python] Read vindex vector indexes

[JingsongLi]

Summary

This PR flattens paimon-vector into a single jar module backed by paimon-vector-index-java 0.1.0, removing the old paimon-vector-jni submodule. It also adds Python read support for vindex vector indexes through paimon-vindex 0.1.0 and covers Java-write/Python-read interop.

Changes

• Convert paimon-vector from a parent module with paimon-vector-index and paimon-vector-jni children into one module that depends on paimon-vector-index-java 0.1.0.
• Move the vector global index factories/readers/writers into the top-level paimon-vector source tree and load the native library from the released Java artifact.
• Add a Python paimon-vindex vector global index reader and wire it into vector search reader dispatch for ivf-flat, ivf-pq, ivf-hnsw-flat, and ivf-hnsw-sq.
• Add optional Python packaging/dev dependency entries for paimon-vindex==0.1.0.
• Add Java/Python mixed tests: Java writes a vindex-backed vector index and Python reads/searches it; run_mixed_tests.sh now runs that path on Python >= 3.9.

Testing

• python -m py_compile paimon-python/pypaimon/table/source/vector_search_read.py paimon-python/pypaimon/globalindex/vindex/vindex_vector_global_index_reader.py paimon-python/pypaimon/tests/e2e/java_py_read_write_test.py
• bash -n paimon-python/dev/run_mixed_tests.sh
• git diff --check
• mvn -pl paimon-vector -am -Pfast-build -DfailIfNoTests=false -Dtest=NativeVectorGlobalIndexerFactoryTest,SeekableStreamVectorIndexInputTest,NativeVectorGlobalIndexTest,org.apache.paimon.JavaPyE2ETest#testVindexVectorIndexWrite test -Drun.e2e.tests=true
• PYTHONPATH=/tmp/paimon-vindex-site:${PYTHONPATH:-} python -m pytest java_py_read_write_test.py::JavaPyReadWriteTest::test_read_vindex_vector_index -v
• mvn -pl paimon-vector -am -DskipTests compile

Notes

paimon-vector has not been released yet, so this intentionally does not preserve compatibility with the old two-submodule layout.

[XiaoHongbo-Hope]

+1