Fix #19363 by using pprName' {Applied,Infix} in the right places
It was revealed in #19363 (closed) that the Template Haskell pretty-printer implemented
in Language.Haskell.TH.Ppr
did not pretty-print infix names or symbolic names
correctly in certain situations, such as in data constructor declarations or
fixity declarations. Easily fixed by using pprName' Applied
(which always
parenthesizes symbolic names in prefix position) or pprName' Infix
(which
always surrounds alphanumeric names with backticks in infix position) in the
right spots.
Fixes #19363 (closed).