HAL-SWH - connectivity tests

We are currently exchanging through email or face to face meetings on the connectivity subject with Bruno Marmol.

So far so good.

I don't remember all the details but this iteratively led to improvments:

relaxed api constraint without the relaxed model constraint led to a 500 error (fixed)
links were not fully qualified urls (fixed) - which led to swh-web#806 (closed) (fixed)
some deposit names were not consistent everywhere (fixed)
post deposit action to add checks on tarball (developed)
...

Now remains the metadata exchange which is in progress.

Migrated from T820 (view on Phabricator)