feat!: migrate FTS from tantivy to lance-index (#1483)

Lance now supports FTS, so add it into lancedb Python, TypeScript and
Rust SDKs.

For Python, we still use tantivy based FTS by default because the lance
FTS index now misses some features of tantivy.

For Python:
- Support to create lance based FTS index
- Support to specify columns for full text search (only available for
lance based FTS index)

For TypeScript:
- Change the search method so that it can accept both string and vector
- Support full text search

For Rust
- Support full text search

The others:
- Update the FTS doc

BREAKING CHANGE: 
- for Python, this renames the attached score column of FTS from "score"
to "_score", this could be a breaking change for users that rely the
scores

---------

Signed-off-by: BubbleCal <bubble-cal@outlook.com>

python/python/tests/test_db.py

@@ -22,7 +22,8 @@ import pytest
 from lancedb.pydantic import LanceModel, Vector
 
 
-def test_basic(tmp_path):
+@pytest.mark.parametrize("use_tantivy", [True, False])
+def test_basic(tmp_path, use_tantivy):
     db = lancedb.connect(tmp_path)
 
     assert db.uri == str(tmp_path)
@@ -55,7 +56,7 @@ def test_basic(tmp_path):
     assert len(rs) == 1
     assert rs["item"].iloc[0] == "foo"
 
-    table.create_fts_index(["item"])
+    table.create_fts_index("item", use_tantivy=use_tantivy)
     rs = table.search("bar", query_type="fts").to_pandas()
     assert len(rs) == 1
     assert rs["item"].iloc[0] == "bar"