Python: bytearray body support for ASGI module.

@filiphanes requested support for bytearray
and memoryview in the request body here:
<https://github.com/nginx/unit/issues/648>

This patch implements bytearray body support only.
Memoryview body still need to be implemented.

test/python/body_bytearray/asgi.py

@@ -0,0 +1,20 @@
+async def application(scope, receive, send):
+    assert scope['type'] == 'http'
+
+    body = b''
+    while True:
+        m = await receive()
+        body += m.get('body', b'')
+        if not m.get('more_body', False):
+            body = bytearray(body)
+            break
+
+    await send(
+        {
+            'type': 'http.response.start',
+            'status': 200,
+            'headers': [(b'content-length', str(len(body)).encode())],
+        }
+    )
+
+    await send({'type': 'http.response.body', 'body': body})

test/test_asgi_application.py

@@ -218,6 +218,14 @@ def test_asgi_application_shm_ack_handle():
     assert resp['body'] == body, 'keep-alive 1'
 
 
+def test_asgi_application_body_bytearray():
+    client.load('body_bytearray')
+
+    body = '0123456789'
+
+    assert client.post(body=body)['body'] == body
+
+
 def test_asgi_keepalive_body():
     client.load('mirror')