Collection name under test is equal to the test module name, without `.py` suffix.
* Helps by debugging/tracing failed tests and find relevant logs lines in qdrant log files
* Opens up a possibility to run tests in parallel, given that there are no data sharing
between test modules
Change details:
* defined module scoped `collection_name` fixture in `conftest.py`
* removed `collection_name` module variable
* each test signature modified to declare the dependency to `collection_name` fixture
* `@pytest.mark.parametrize` migrated to `@pytest-cases.parametrize` in cases when
`collection_name` was used as the value
* `QDRANT_HOST` variable is used by all openapi tests, removed its copies from
`test_multi_vector_uint8.py`, `test_multi_vector_unnamed.py`, `test_query.py`,
`test_shard_snapshot.py`, and `test_snapshot.py`
* Added optional `QDRANT_HOST_HEADERS` env variable to set custom HTTP headers
in order to reach Qdrant instance behind a reverse proxy. The content of the
variable is JSON payload, e.g. `{"host": "qdrant.local"}`
* Adapted `./tests/basic_*.sh` scripts to aware of `QDRANT_HOST_HEADERS` env variable
