Handle show and use command completions by providing pre- and post-processing for these types. Specifically, if a user attempts to complete show and use, we run completions for show( and use(, possibly including the prefixes the user already provided, and then strip away the parentheses and quotes again when finished completing.

Note: Search for directShellCommand. Should be use, show, exit, quit, it and cls. Snippet commands work in a similar way.