[pp] Remove special tag type and handler from Pp.

For legacy reasons, pretty printing required to provide a "tag"
interpretation function `pp_tag`. However such function was not of much
use as the backends (richpp and terminal) hooked at the `Format.tag`
level.

We thus remove this unused indirection layer and annotate expressions
with their `Format` tags.

This is a step towards moving the last bit of terminal code out of the
core system.

0 files changed, 0 insertions, 0 deletions