Right now, when opening a shell with `script/ghci`, you can encounter
a tremendous slowdown by turning on pretty-printing (with `pretty`)
then printing any value (`[0..3]` should work).
This stems from the fact that our `.ghci` specifies the `prettyShow`
function, defined in Semantic.Util, as its `-interactive-print`
function. While this is a good choice of a pretty-printer, the fact
that it is in Util, a file which imports many modules and uses fancy
types, is not good: pretty-printing cannot begin until Util is
recompiled and linked in. This explains why benchmarking this slowdown
revealed nothing but `dlsym` calls: we thought it was due to linking
in the tree-sitter libraries, but it was actually waiting for Util to
compile and link in.
The fix is simple: define `prettyShow` in another module. This should
provide significant speedups to our developer workflow.
