This is needed as we get software instances by their reference and not
their relative urls

slapos_jio_api_style: Add related key to be able to search instance from host compute node reference

* NotFound Errors are now handled by API

Can replace the following SlapTool calls:
* softwareReleaseError
* availableSoftwareRelease
* buildingSoftwareRelease
* destroyedSoftwareRelease

This new Web Service can be configured to define a list of entry points associated to JSON Form.

Those entry points are accessed by a client by doing an HTTP Post with a JSON input body.
The input JSON is validated by the JSON Form.

An output JSON body is expected as response.

It allows to reuse the erp5js header gadget.

See nexedi/erp5!2039