Support no folder debugging

Hi VS Code PM here 👋

1. Purple no folder VS Code -> create a new `kotlin` file
2. Press `F5` -> notice how we offer the user to download your extension 👏
3. Now the user presses `F5` again and wants to debug, but nothing happens since `kotlin` is not supporting single folder debugging

Easiest to do this is to have a dynamic `resolveDebugConfiguartion` that will provide a launch configuration on the fly. [Example](https://github.com/microsoft/vscode-mock-debug/blob/main/src/activateMockDebug.ts#L161)

Apart from that consider contributing to the Editor title area menu, such that a Play button would appear in the Editor Title area (picture below). Example how to do this https://github.com/microsoft/vscode-mock-debug/blob/main/package.json#L80

I think both of these are super important and would really love that we improve this experience 💯
Let me know if I can help somehow. I am also open to a quick 30 min meeting where we can discuss about the new cool VS Code debug features that kotlin could potentially adopt.

Start by reading the referenced resolveDebugConfiguration example in vscode-mock-debug and its package.json editor-title menu example, then locate the corresponding debug activation and extension-contribution entry points in vscode-kotlin. Done means pressing F5 for a Kotlin file in a no-folder window can start debugging and the requested Play action appears in the editor title area.

Written by the indexing model from the issue text.