feat(backend): add recent searches

[Oran-Dan]

Description of change

I have setup the backend to deliver "recent_searches" functionality. It is a simple Vec storing the recent search_terms. If the same search_term is entered again (case-insensitive) it will be removed from the list and added back on top.

Also i have changed the CoreState and core_state fields to CoreUtils and core_utils.

Links to any relevant issues

84

How the change has been tested

I have made extra integration tests in the unime/src-tauri/tests folder, including new .json fixtures

Definition of Done checklist

Add an x to the boxes that are relevant to your changes.

• [x] I have followed the contribution guidelines for this project
• [x] I have performed a self-review of my own code
• [x] I have commented my code, particularly in hard-to-understand areas
• [ ] I have made corresponding changes to the documentation
• [x] I have added tests that prove my fix is effective or that my feature works
• [x] New and existing unit tests pass locally with my changes

[daniel-mader]

Please run cargo test inside identity-wallet to update the bindings.