feat(vscode): add kcm debugging configuration

This adds a new debugging configuration for KCMs in VS Code. This makes running and debugging KCMs much easier and more convenient.

Test Plan

• Open a project in VS Code that has KCMs, for example plasma-workspace

• If the project already has a .vscode config folder, delete it and rebuild the project with kde-builder to regenerate the configs with the new options

• Ensure the recommended extensions are enabled as directed in the setup instructions

• Open the build target selector by clicking the button (defaults to all):

• Filter for KCMs by typing kcm_, and choose one of the options marked MODULE_LIBRARY that represents a KCM:

• Switch the launch config to the new kcm option, then run:

• The config directs kde-builder to rebuild the project, then runs the kcm:

• Switch to different KCMs by stopping debug session, changing the build target to a different kcm_$module target, and starting debug