This groups the DATA and METADATA argument of `jupyter-org-result`
into a CONTENT argument to finish up a change made in a previous
commit that removed `jupyter-loop-over-mime`. The METADATA argument
is rarely if every used, so it doesn't make sense to have all those
method implementations have to provide it.
* jupyter-org-client.el
(jupyter-org--image-result): Change group DATA and METADATA into a
CONTENT argument. Change argument ordering. Update all callers.
Cleanup the documentation to reflect the changes.
(jupyter-org-result): Similarly, group those two arguments into the
one argument. Update all callers in this file, also...
* README.org: ...here
* jupyter-R.el: ...here
* jupyter-python.el: ...and here
