feat(gatsby-plugin-sass): Accept css-loader options

[dustinhorton]

v2 changed how dashes/hyphens in class names handled by css modules were treated: #5458. This was burdensome as it required changing all classNames that utilized dashes.

This allows overriding that change, almost entirely by copying prior art from @yeskunall & @pieh (#9237).

[dustinhorton]

@pieh Need anything else from me?

[DSchau]

Looking good! Left a few comments, my biggest concern is about the snapshots, but doesn't look like you'd have done anything to break that so just want to double check!

[pieh]

Thanks @dustinhorton!

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