Rework implementation support for OCM storage backends

[mandelsoft]

Description

• step 1: introduce a clear three layer approach
  • layer 1: the user facing api in contexts/ocm
  • layer 2: the support layer, here is the implementation of standard behaviour and backend-agnostic API functionality
    ´ like view management. It consistently introduced two kinds of objects
    a) the view object, providing the final user facing interface including the Dup() functionality
    b) common implementation objects referred by view objects, they will implement central functionality based o the
    implementation interface
  • laver 3: the storage backend implementations of the layer two implementation interfaces.
• step 2: simplify the implementation interfaces
• step 3: move down standard implementations to the base layer.
• step 4: provide simplified repository implementation support using a single implementation interface.

What type of PR is this? (check all applicable)

• 🍕 Feature
• 🐛 Bug Fix
• 📝 Documentation Update
• 🎨 Style
• 🧑‍💻 Code Refactor
• 🔥 Performance Improvements
• ✅ Test
• 🤖 Build
• 🔁 CI
• 📦 Chore (Release)
• ⏩ Revert

Related Tickets & Documents

• Related Issue # (issue)
• Closes # (issue)
• Fixes # (issue)

Remove if not applicable

Screenshots

Added tests?

• 👍 yes
• 🙅 no, because they aren't needed
• 🙋 no, because I need help
• Separate ticket for tests # (issue/pr)

Please describe the tests that you ran to verify your changes. Provide instructions so we can reproduce. Please also list any relevant details for your test configuration

Added to documentation?

• 📜 README.md
• 🙅 no documentation needed

Checklist:

• My code follows the style guidelines of this project
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have made corresponding changes to the documentation
• My changes generate no new warnings
• I have added tests that prove my fix is effective or that my feature works
• New and existing unit tests pass locally with my changes
• Any dependent changes have been merged and published in downstream modules