Required in swh-core >= v0.0.45.

Prior to this commit, we'd need to add the url with the /1 suffix. This now
automatically add it. This avoids confusing errors when not provided.

This also adds some unit tests to the cli.

Same as provider url

Release artifact is now specified for a deposit
with a review of the loading specification
Added diagram about the deposit status
Fixes on test scenaris as well

This reverts commit 216d0f74.

place technical details in a new spec document
review text and update to current state

It no longer needs that argument.

Related T1508

Without this, some dependencies from swh.core[http] are not installed
(because swh.core, without extras, is installed first from
requirements-swh.txt).

Probably similar to this issue https://github.com/pypa/pip/issues/6506

Related T1650
Related T1648

Related T1648

This is in compliance to the documentation and the existing behavior. Those
checks can be reinstated further down the line.

Related T1650

```
swh deposit admin deposit reschedule --help
```

This commands is for admin use since it needs writable access

Related T1703

to prevent the ugly 'swh deposit deposit' in favor of:

  swh deposit upload

'swh' being the new master command group (defined in swh.core); so:

  swh deposit --help

works. The 'admin' (deposit server management) is only available if the
swh.deposit[server] optional package is installed.

Ensure the 'swh-deposit' still works for now.

in the swh.deposit.cli namespace.