Changes

contrib: add utility to receive ES2+handleDownloadProgressInfo calls

We already have a tool to work with the ES2+ API provided by an SMDP+
(es2p_client.py) With this tool we can only make API calls towards
an SMDP+. However, SGP.22 also defines a "reverse direction" ES2+
interface through wich the SMDP+ may make API calls towards the MNO.

At the moment the only possible MNO originated API call is
ES2+handleDownloadProgressInfo. Let's add a simple tool that runs a
HTTP server to receive and log the ES2+handleDownloadProgressInfo
requests.

Related: SYS#7825
Change-Id: I95af30cebae31f7dc682617b1866f4a2dc9b760c