feat: add support for add to async python API (#1037)

In order to add support for `add` we needed to migrate the rust `Table`
trait to a `Table` struct and `TableInternal` trait (similar to the way
the connection is designed).

While doing this we also cleaned up some inconsistencies between the
SDKs:

* Python and Node are garbage collected languages and it can be
difficult to trigger something to be freed. The convention for these
languages is to have some kind of close method. I added a close method
to both the table and connection which will drop the underlying rust
object.
* We made significant improvements to table creation in
https://github.com/lancedb/lancedb/commit/cc5f2136a61234a9cdbe20e19c56459db8ca1051
for the `node` SDK. I copied these changes to the `nodejs` SDK.
* The nodejs tables were using fs to create tmp directories and these
were not getting cleaned up. This is mostly harmless but annoying and so
I changed it up a bit to ensure we cleanup tmp directories.
* ~~countRows in the node SDK was returning `bigint`. I changed it to
return `number`~~ (this actually happened in a previous PR)
* Tables and connections now implement `std::fmt::Display` which is
hooked into python's `__repr__`. Node has no concept of a regular "to
string" function and so I added a `display` method.
* Python method signatures are changing so that optional parameters are
always `Optional[foo] = None` instead of something like `foo = False`.
This is because we want those defaults to be in rust whenever possible
(though we still need to mention the default in documentation).
* I changed the python `AsyncConnection/AsyncTable` classes from
abstract classes with a single implementation to just classes because we
no longer have the remote implementation in python.

Note: this does NOT add the `add` function to the remote table. This PR
was already large enough, and the remote implementation is unique
enough, that I am going to do all the remote stuff at a later date (we
should have the structure in place and correct so there shouldn't be any
refactor concerns)

---------

Co-authored-by: Will Jones <willjones127@gmail.com>

python/ASYNC_MIGRATION.md

@@ -15,10 +15,24 @@ need to use `await` to call these functions.
 
 ## Connection
 
-No changes yet.
+* The connection now has a `close` method.  You can call this when
+  you are done with the connection to eagerly free resources.  Currently
+  this is limited to freeing/closing the HTTP connection for remote
+  connections.  In the future we may add caching or other resources to
+  native connections so this is probably a good practice even if you aren't using remote connections.
+
+  In addition, the connection can be used as a context manager which may
+  be a more convenient way to ensure the connection is closed.
+
+  It is not mandatory to call the `close` method.  If you don't call it
+  the connection will be closed when the object is garbage collected.
 
 ## Table
 
+* The table now has a `close` method, similar to the connection.  This
+  can be used to eagerly free the cache used by a Table object.  Similar
+  to the connection, it can be used as a context manager and it is not
+  mandatory to call the `close` method.
 * 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.