[Feature Request]: Support folder icon associations based on name suffix

## Problem Folder names using dot notation (common in .NET solutions) like `MyApp.Tests`, `MyApp.Api`, or `MyApp.Domain` do not receive folder icons based on their suffix. For example, a folder named `Project.Tests` should ideally display the `folder-test` icon, since its suffix clearly signals its purpose — but today it falls back to the default folder icon. This is a pattern widely used in .NET, Java, and other ecosystems where project directories are named with a dot-separated namespace convention. ## Current behavior `folderNames` only supports exact name matching. A folder named `Project.Tests` does not match the existing `tests` / `test` associations in `folderIcons.ts`. ## Expected behavior The extension should be able to match folder icons based on the **suffix** of a dotted folder name. For example: | Folder name | Matched suffix | Expected icon | |-------------------|----------------|--------------------| | `MyApp.Tests` | `Tests` | `folder-test` | | `MyApp.Api` | `Api` | `folder-api` | | `MyApp.Application` | `Application` | `folder-app` | ## Proposed solution Introduce a new matching strategy in the folder icon resolution logic that, **after failing an exact match**, splits the folder name by `.` and attempts to match the last segment against existing `folderNames` associations. This would be purely additive and backward-compatible — exact matches would still take priority.