feat: port create_table to the async python API and the remote rust API (#1031)

I've also started `ASYNC_MIGRATION.MD` to keep track of the breaking
changes from sync to async python.

python/ASYNC_MIGRATION.md

@@ -0,0 +1,24 @@
+# Migration from Sync to Async API
+
+A new asynchronous API has been added to LanceDb.  This API is built
+on top of the rust lancedb crate (instead of being built on top of
+pylance).  This will help keep the various language bindings in sync.
+There are some slight changes between the synchronous and the asynchronous
+APIs.  This document will help you migrate.  These changes relate mostly
+to the Connection and Table classes.
+
+## Almost all functions are async
+
+The most important change is that almost all functions are now async.
+This means the functions now return `asyncio` coroutines.  You will
+need to use `await` to call these functions.
+
+## Connection
+
+No changes yet.
+
+## Table
+
+* Previously `Table.schema` was a property.  Now it is an async method.
+* The method `Table.__len__` was removed and `len(table)` will no longer
+  work.  Use `Table.count_rows` instead.