[feature]: Format TCSS

[rodrigogiraoserrao]

From Discord,

I just installed the Textual CSS syntax highlighter, which unfortunately doesn't do stuff like formatting, so I thought about setting the formatter to the CSS formatter, but that doesn't seem to work (I edited the settings.json and copied the editor.defaultFormatter entry from [CSS] to [Textual CSS]).

For reference:

"[Textual CSS]": {
    "editor.defaultFormatter": "vscode.css-language-features"
}

Can we make the extension format TCSS as CSS would be usually formatted..?