Vscode-powershell: Provide commonly used ISE hotkey compatibility

[daviwil]

There are a few hotkeys that are commonly used in the ISE, we should try to provide a way to replicate them. @dfinke provided a Gist with all of the ISE's hotkeys and pointed out that these seem to be the most used which don't have analogues in VS Code yet:

Ctrl+D GoToConsoleShortcut
Ctrl+I GoToEditorShortcut
Ctrl+R ToggleScriptPaneShortcut [Ctrl+` in vsc]
Ctrl+M ToggleOutliningExpansionShortcut [ctrl+k ctrl+0 in vsc]

Since some of these keybindings may conflict with built in VS Code bindings, it'd be better to provide these as an opt-in action which will modify the user's VS Code keybindings.

[rkeithhill]

FWIW I used ISE for years before switching over to VSCode w/PS extension. I used Ctrl+D and Ctrl+I quite a bit - Ctrl+R less so and Ctrl+M not at all. Having a kbd shortcut to quickly switch focus between editor and terminal would be handy but not just for PowerShell. I do some PHP and ASP.NET MVC in VSCode and it would be handy for that as well. :-)

[Bill-Stewart]

Agree they should be opt-in.