Pretty-printer incorrectly considers reserved ps names as needing quoting #3482

I've just realised that, since #699, the function isUnquotedKey is still more conservative than necessary when it is deciding what can be used as an unquoted record label with respect to reserved PureScript identifiers. For example:

> {} :: { data :: Int }
Error found:
in module $PSCI
at  line 1, column 1 - line 1, column 3

  Type of expression lacks required label "data".

while checking that expression {}
  has type { "data" :: Int
           }              
in value declaration it

"data" doesn't need quoting in the error, because we do in fact allow it as an unquoted record key.