[core] aiohttp multipart/form-data drops data when files included

[kristapratico]

If both files and data are passed in the request, only what's in files gets added to aiohttp.FormData in the code below. data gets dropped and is not encoded into request.

azure-sdk-for-python/sdk/core/azure-core/azure/core/pipeline/transport/_aiohttp.py

Lines 158 to 175 in 2d0123c

	def _get_request_data(self, request):
	"""Get the request data.
	:param request: The request object
	:type request: ~azure.core.pipeline.transport.HttpRequest or ~azure.core.rest.HttpRequest
	:rtype: bytes or ~aiohttp.FormData
	:return: The request data
	"""
	if request.files:
	form_data = aiohttp.FormData()
	for form_file, data in request.files.items():
	content_type = data[2] if len(data) > 2 else None
	try:
	form_data.add_field(form_file, data[1], filename=data[0], content_type=content_type)
	except IndexError as err:
	raise ValueError("Invalid formdata formatting: {}".format(data)) from err
	return form_data
	return request.data

For example, if I'm doing multipart/form-data with files and data={"response_format": "srt"}, I would expect my request body to look like:

b'--df13136170d9e03a0e82350af6b2afb7\r\nContent-Disposition: form-data; name="response_format"\r\n\r\nsrt\r\n--df13136170d9e03a0e82350af6b2afb7\r\nContent-Disposition: form-data; name="file"; filename="hello.m4a"\r\nContent-Type: application/octet-stream\r\n\r\n\x00\x00\x00\x18ftypmp42\x00\x00\x00\x00mp41isom\x00\x00\x00(uuid\\\xa7\x08\xfb2\x8eB\x05\xa8ae\x0e\xca\n\x95\x96\x00\x00\x00\x0c10.0.22621.0\x00\

Updating the code to something like the below seems to work.

if request.files:
    form_data = aiohttp.FormData(request.data or {})