port remote connection client into lancedb (#194)

* to_df() is now async, added `to_df_blocking` to convenience
* add remote lancedb client to public lancedb
* make lancedb connection class understand url scheme
`lancedb+<connection_type>://<host>:<port>`.

python/tests/test_e2e_remote_db.py

@@ -0,0 +1,28 @@
+#  Copyright 2023 LanceDB Developers
+#
+#  Licensed under the Apache License, Version 2.0 (the "License");
+#  you may not use this file except in compliance with the License.
+#  You may obtain a copy of the License at
+#      http://www.apache.org/licenses/LICENSE-2.0
+#
+#  Unless required by applicable law or agreed to in writing, software
+#  distributed under the License is distributed on an "AS IS" BASIS,
+#  WITHOUT WARRANTIES OR CONDITIONS OF ANY KIND, either express or implied.
+#  See the License for the specific language governing permissions and
+#  limitations under the License.
+
+from lancedb import LanceDBConnection
+
+import numpy as np
+
+import pytest
+
+# TODO: setup integ test mark and script
+
+
+@pytest.mark.skip(reason="Need to set up a local server")
+def test_against_local_server():
+    conn = LanceDBConnection("lancedb+http://localhost:10024")
+    table = conn.open_table("sift1m_ivf1024_pq16")
+    df = table.search(np.random.rand(128)).to_df()
+    assert len(df) == 10