feat: Allow import-trees to be used in argument as if they were paths.

[vic]

No description provided.

[Copilot]

Pull Request Overview

This PR introduces support for treating import-tree objects as if they were filesystem paths.

• Updates default.nix by adding helper functions for handling import-trees.
• Adds tests in checkmate.nix to verify that import-trees work as arguments.
• Updates README.md to document the new behavior.

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated no comments.

File	Description
default.nix	Adds helper functions (listFilesRecursive, treeFiles, isImportTree) to enable import-tree handling.
checkmate.nix	Introduces a test case validating import-tree objects used as paths.
README.md	Updates documentation to describe the new usage of import-tree objects.

Comments suppressed due to low confidence (2)

default.nix:33

• [nitpick] Consider renaming 'treeFiles' to 'importTreeFiles' to better reflect its purpose and improve code clarity in handling import-tree objects.

          treeFiles = t: (t.withLib lib).leafs.result;

checkmate.nix:170

• [nitpick] Consider using a more conventional and concise attribute name (e.g., 'test_import_tree_path_handling') instead of a long descriptive string to maintain consistency and ease of reference.

        import-tree."test can take other import-trees as if they were paths" = {