Add various new requests to the Patchwork class, so we can obtain the
required information. This includes cover letters and comments.

Signed-off-by: Simon Glass <sjg@chromium.org>

Add support to the status module for reading and supporting cover
letters, including comments. Plumb this through to the patchwork module.
The actual support in the latter is not yet integrated.

Signed-off-by: Simon Glass <sjg@chromium.org>

Patman normally sends multiple concurrent requests to the patchwork
server, as this is faster. Provide an option to disable this.

Signed-off-by: Simon Glass <sjg@chromium.org>

Now that all the pieces are in place, switch over from using an executor
to using asyncio.

While we are here, import defaultdict to avoid needing to specify its
module.

Signed-off-by: Simon Glass <sjg@chromium.org>

The cover letter has some information on each patch, so allow this to be
stored in the Patch object.

Signed-off-by: Simon Glass <sjg@chromium.org>

Instead of passing the URL and function to each call, put the fake
into the Patchwork object instead.

Signed-off-by: Simon Glass <sjg@chromium.org>

Expand the patchwork module so that it can match the current
requirements of the 'patman status' command, i.e. reading the state of a
series and the patches associated with it.

Since the format of each patchwork response is a little tricky to
understand, add examples in comments at the top of each function.

Signed-off-by: Simon Glass <sjg@chromium.org>

These relate to information obtained from the patchwork server, so move
their definition into the new patchwork module.

Signed-off-by: Simon Glass <sjg@chromium.org>

At present the patchwork implementation is very simple, just consisting
of a function which calls the REST API.

We want to create a fake patchwork for use in tests. So start a new
module to encapsulate communication with the patchwork server.

Use asyncio since it is easier to handle lots of concurrent requests
from different parts of the code.

Signed-off-by: Simon Glass <sjg@chromium.org>