feat!: change default read_consistency_interval=5s (#2281)

Previously, when we loaded the next version of the table, we would block
all reads with a write lock. Now, we only do that if
`read_consistency_interval=0`. Otherwise, we load the next version
asynchronously in the background. This should mean that
`read_consistency_interval > 0` won't have a meaningful impact on
latency.

Along with this change, I felt it was safe to change the default
consistency interval to 5 seconds. The current default is `None`, which
means we will **never** check for a new version by default. I think that
default is contrary to most users expectations.

python/python/tests/test_table.py

@@ -32,7 +32,11 @@ def test_basic(mem_db: DBConnection):
     table = mem_db.create_table("test", data=data)
 
     assert table.name == "test"
-    assert "LanceTable(name='test', version=1, _conn=LanceDBConnection(" in repr(table)
+    assert (
+        "LanceTable(name='test', version=1, "
+        "read_consistency_interval=datetime.timedelta(seconds=5), "
+        "_conn=LanceDBConnection("
+    ) in repr(table)
     expected_schema = pa.schema(
         {
             "vector": pa.list_(pa.float32(), 2),