Request: Make the CTRL + backspace behavior for paths apply to more types of paths or allow plugins to customize it

Currently the CTRL + backspace behavior is [hardcoded](https://github.com/Flow-Launcher/Flow.Launcher/blob/dev/Flow.Launcher/MainWindow.xaml.cs#L484) to:

1. If the query is a valid path, remove everything until the last '`\`' that isn't at the end, e.g.:
* `C:\Asd\Some Example` -> `C:\Asd\`
* `C:\Asd\Some Example\` -> `C:\Asd\`
2. Otherwise, behave normally:
* `Example\Asd\Some Example` -> `Example\Asd\Some `
* `Example\Asd\Some Example\` -> `Example\Asd\Some Example`

I'd like for the behavior of the first case to apply to more types of paths since plugins like the registry's or a Windows Tasks plugin I'm making have paths such as:
* `HKCU\Keyboard Layout\Preload\`
* `\Microsoft\Windows\AccountHealth\`

These paths don't follow the format of letter + colon + slash (e.g. `C:\`) so they aren't considered valid paths.