Add async upload functions

[ryanshrott]

Would you consider adding some native async methods like this?

    async def aupload(self, files: list[Path | str] | Generator, chunk_size=64 * 1024) -> list[dict]:
        """
        Upload files to Amazon Photos

        @param files: list of files to upload
        @param chunk_size: optional size to chunk files into during stream upload
        @return: the upload response
        """

        async def stream_bytes(file: Path) -> bytes:
            async with aiofiles.open(file, 'rb') as f:
                while chunk := await f.read(chunk_size):
                    yield chunk

        async def upload_file(client: AsyncClient, file: Path):
            logger.debug(f'Upload start: {file.name}')
            file = Path(file) if isinstance(file, str) else file
            
            async with aiofiles.open(file, 'rb') as f:
                file_content = await f.read()
                
            r = await client.post(
                'https://content-na.drive.amazonaws.com/v2/upload',
                data=stream_bytes(file),
                params={
                    'conflictResolution': 'RENAME',
                    'fileSize': str(len(file_content)),
                    'name': file.name,
                    'parentNodeId': self.root,
                },
                headers={
                    'content-length': str(len(file_content)),
                    'x-amzn-file-md5': hashlib.md5(file_content).hexdigest(),
                }
            )
            data = r.json()
            logger.debug(f'Upload complete: {file.name}')
            logger.debug(f'{data = }')
            return data

        async with AsyncClient(
            http2=True,
            timeout=60,
            follow_redirects=True,
            headers=self.client.headers,
            cookies=self.client.cookies
        ) as client:
            fns = [upload_file(client, file) for file in files]
            return await asyncio.gather(*fns)