Refactor hierarchies & test-runner — for type-hinting

[nolar]

Refactor hierarchies & test-runner toolkits to prepare for the overall type-hinting.

Issue : #194

Description

All the changes are done as a preparation for the throughout type-hinting in the code base. Resolving the cyclic imports becomes important. The whole refactoring is split into few PRs (one per concept) for ease of review.

Create a new group (package) of modules — toolkits — for all modules which are not directly involved in the operators functionality, but can be very helpful to ease some common tasks in those operators:

• Object hierarchy management (ownership, labelling, naming, namespacing, etc).
• Operator testing.

The name kopf.testing is a documented public interface, so it remains — just converted from a package to a module now.

Types of Changes

• Refactor/improvements

There are no behavioural changes. Only the code refactoring. The tests show that all the protocols and interfaces are kept in place — except for the imports of the internal modules (not exposed via kopf/__init__.py).

[zincr]

🤖 zincr found 0 problems , 0 warnings

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[jonathanbeber]

+1