refactor: rework highlight mode, colorful, flipped and blind to pure css

[Miodec]

Also adds a .typed class to all words that were already typed to allow for easier advanced theming.

Closes #5561

[fehmer]

• themes rgb, grape, aurora, fire, trance in mode flipped does not use the animation
• not sure if theme rainbow trail should use the animation without fading to while in flipped mode

[fehmer]

I'm not sure if this is on purpose. The "special" themes like rainbow trail de-highlight the typed letters even if you are in e.g. `highlight next word" mode. "Regular" themes highlight the complete word while you type it.

Theme 9009

Theme rainbow trail

[fehmer]

• rainbow trail in flipped mode + word highlight does not use fadeout for typed words
• grape, fire, trance and aurora theme non-flipped + word highlight de-highlights typed letter