Feature request: Run command that is result of evaluation

[timothypratley]

A less intrusive version of #2679
Instead of checking every value evaluated,
Custom commands can optionally specify that their result should be interpreted as a command.

    {
        "name": "Eval Current Form as Command",
        "key": "a",
        "repl": "clj",
        "snippet": "$current-form",
        "command": []
    },

With this custom command, you can activate it with the following data:

 [:vscode.diff
 [:File "./notebooks/visualization_in_editors.clj"]
 [:Uri.parse "/Users/timothypratley/git/kindly-render/examples/basic/page.clj"]
 "diff title"
 {:viewColumn -2}]

[:simpleBrowser.api.open "https://calva.io/" {:viewColumn -2}]

Tools can make use of this when they supply resources/calva.exports/config.edn, see https://calva.io/custom-commands/#snippets-inside-deps