Bug 36565: Unit tests

Bug 36565: Unit tests

This patch introduces tests on the OpenAPI spec so that all tags used in
path definitions have their corresponding entry at the top level 'tags'
section.

This it important for correctly rendering the API documentation.

Signed-off-by: Tomas Cohen Arazi <tomascohen@theke.io>
Signed-off-by: David Nind <david@davidnind.com>
Signed-off-by: Martin Renvoize <martin.renvoize@ptfs-europe.com>
Signed-off-by: Katrin Fischer <katrin.fischer@bsz-bw.de>