* consider length of multivectors for rate limiter
* add openapi test
* organize imports
* better cost estimation for sparse vectors
* restore groups openapi test
* address @timvisee's review
* Fix consensus test
Although test logic passes the assertions, the test might fail
if during the teardown the created collection is not deleted,
because the client could not reach the database due to networking issue.
In order to make test executions more robust, collection deletes
are retried in case of networking issues.
If `wait=true` param is not set for delete vector API calls, a test asserting later
that data are gonna can become flaky, because at the assertion time the data could be
still there.
The following files contain such tests at the moment:
* `test_multi_vector_uint8.py`
* `test_multi_vector.py`
* `test_multi_vector_unnamed.py`
* `test_optional_vectors.py`
In order to fix these and prevent the flakiness of future test,
`request_with_validation` helper add `wait=true` param, if it is not set
for delete vector calls.
* `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
