feat(python): add search() method to async API (#2049)

Reviving #1966.

Closes #1938

The `search()` method can apply embeddings for the user. This simplifies
hybrid search, so instead of writing:

```python
vector_query = embeddings.compute_query_embeddings("flower moon")[0]
await (
    async_tbl.query()
    .nearest_to(vector_query)
    .nearest_to_text("flower moon")
    .to_pandas()
)
```

You can write:

```python
await (await async_tbl.search("flower moon", query_type="hybrid")).to_pandas()
```

Unfortunately, we had to do a double-await here because `search()` needs
to be async. This is because it often needs to do IO to retrieve and run
an embedding function.

python/python/tests/test_remote_db.py

@@ -338,6 +338,7 @@ def test_query_sync_empty_query():
             "filter": "true",
             "vector": [],
             "columns": ["id"],
+            "prefilter": False,
             "version": None,
         }
 
@@ -412,6 +413,7 @@ def test_query_sync_fts():
                 "columns": [],
             },
             "k": 10,
+            "prefilter": True,
             "vector": [],
             "version": None,
         }
@@ -429,6 +431,7 @@ def test_query_sync_fts():
             },
             "k": 42,
             "vector": [],
+            "prefilter": True,
             "with_row_id": True,
             "version": None,
         }
@@ -455,6 +458,7 @@ def test_query_sync_hybrid():
                 },
                 "k": 42,
                 "vector": [],
+                "prefilter": True,
                 "with_row_id": True,
                 "version": None,
             }