Ask which languages to lint

[nzakas]

Now that we can lint JSON and Markdown, we should incorporate this into the setup flow.

First Question

The first question should now be (with checkboxes):

What do you want to lint?
(x) JavaScript
( ) JSON
( ) JSON with comments
( ) JSON5
( ) Markdown

The JavaScript option should be checked by default and if unchecked, we should add this to the config:

{
    ignores: ["**/*.js", "**/*.cjs", "**/*.mjs"]
}

If Markdown is Checked

If someone checks Markdown, then we should ask (radio buttons):

What flavor of Markdown to you want to lint?
(x) CommonMark
( ) GitHub-Flavored Markdown