Rename prettyprinters test to llvm-support.

Summary: Make room for mlir-support pretty printers that I would like to add next.

Reviewers: dblaikie

Reviewed By: dblaikie

Subscribers: merge_guards_bot, mgorny, rriddle, llvm-commits

Tags: #llvm

Differential Revision: https://reviews.llvm.org/D73726

GitOrigin-RevId: 5a21d2bbb982e431fe0512af2438a1a5e1e13c29
3 files changed