Add arguments to cursorless_vscode_command

[AndreasArvidsson]

Add a third argument to the action that mirrors the extension
https://github.com/pokey/cursorless-vscode/blob/3a83bdcf62e50b8afab79d7c9e9e9c9b74949511/src/actions/CommandAction.ts#L21

Doing so will give the user much more flexibility to define custom commands. In particular, we want to be sure to include the following:

• A list of arguments to pass to the VSCode command itself
• A boolean indicating whether to restore selection after running command
• Default scope type / modifiers / other fields to use for the targets

As mentioned in other issues, we'll create a recipe book for common custom commands

We'll probably allow users to use #554 to represent the extra args, at least for common cases, eg code actions

[pokey]

This would be nice, if nothing else so that you can signal that a command should reset selection

[AndreasArvidsson]

That and commandArgs are probably the most useful.