[Feature] Unit Tests Should Be Rendered In A Tree View

### Request Overview

Instead of providing a long list of (potentially thousands) unit tests in VS Codes Test Explorer, I propose to render the list in a tree-view for easier navigation and comprehensibility.

### Additional Information

Finding the correct test to run currently means to scroll the entire list of unit tests. An alternative that other extensions successfully use is to render the unit tests in a tree-view, similar to a folder structure. This way, the effort of searching for a test is reduced from $O(n)$ to $O(\log(n))$. 😄

A CMake extension that already does this correctly is [CMake Test Explorer](https://marketplace.visualstudio.com/items?itemName=fredericbonnet.cmake-test-adapter).

Start by locating the extension's current VS Code Test Explorer integration and reviewing how unit tests are currently listed. Use CMake Test Explorer as the stated reference for tree navigation. Done means unit tests appear in a navigable tree view while remaining discoverable and runnable.

Written by the indexing model from the issue text.