Add icons to command palette search results

### Description of the new feature / enhancement

Add icons or tags to show what type of result each thing is when searching.

### Scenario when this would be used?

Sometimes, when I am searching for a command palette extension that doesn't have a hotkey, the search brings up both the app and the extension, and it is confusing to have two. For example, dev numbers always comes up twice, with only subtly different icons.

Different icons or tags for extensions, programs, files, commands etc would make this clearer

### Supporting information

_No response_

No file or test is named. Start by locating the Command Palette implementation and its search-result rendering entry point, then compare how extensions, programs, files, and commands are identified. Done means search results visibly distinguish those result types with icons or tags, including the extension-versus-app case described.

Written by the indexing model from the issue text.