Allow using any shell with Shell plugin

Is your feature request related to a problem? Please describe.

It is currently only possible to trigger the command line, Windows Powershell, or the Run command with the Shell plugin. This is not ideal for users who prefer using WSL or newer versions of Powershell. It is possible to run commands in any shell from Flow Launcher, but it requires typing in the specific command for the desired shell each time (e.g. > wsl ls instead of > ls) and it still runs the command in a cmd/Powershell window.

Describe the solution you'd like

Instead of making the user choose from a dropdown list of options, let them type in the command corresponding to the shell they want to use (e.g. pwsh, wsl, etc.)