[SDESK-7372] New Auth mechanism

[MarkLark86]

Purpose

Implement a new Authentication and Authorization mechanism, for use with async resources and endpoints

What has changed

• Move common superdesk.core types into superdesk.core.types, to reduce chance of cyclic imports
• Implement base Authentication mechanism
• Implement base Authorization rules
• Implement Superdesk specific Authentication mechanism (may require further work)
• Expose sync mongo interfaces from async resources, for scenario's where it would be easier to use sync resource
• Support custom error strings in field validators

Resolves: SDESK-7372

[MarkLark86]

This PR is missing the docs and tests. The tests are covered by the Newshub PR that I will create, as it uses this new auth mechanism throughout it's tests.

I will add docs and tests for this core feature in a separate PR, just wanting to get this one in and reviewed.

[eos87]

Looks good to me, I just left a couple of minor comments.

[eos87]

do we need async here?

[MarkLark86]

I've added support for non-async endpoint functions now.