Add unicode support for TH quotes (`[| |]`)
This has been mentioned before but didn't have it's own ticket.
The following where mentioned in #2978 (closed), but the respective patch did not include them:
- For TemplateHaskell:
⟦ ⟧(MATHEMATICAL _ WHITE SQUARE BRACKET) can be used instead of[| |] - For Generics:
⦃ ⦄(_ WHITE CURLY BRACKET) can be used instead of{| |} - For Arrows:
⦇ ⦈(Z NOTATION _ IMAGE BRACKET) can be used instead of(| |)
Generic classes have since been removed and banana brackets were suggested in #10162 (closed) and implemented in D2012, leaving TH quotes.