Morley's `PRINT` shouldn't use show

Description

We use show to display stack values in PRINT, and that's not good.

Steps to reproduce

Pick testassert_square.mtz contract

  test_assert
    CheckSides
    "Sides are %[0] x %[1]"
    { ... }

and run it so that the assertion fails (e.g. with Pair 301 5 parameter).

Prerequisites (if needed):

Expected behaviour

I get Sides are 301 x 5.

Actual behaviour

I will get something like Sides are VInt 301 x VInt 5, and these VInt are not good. The printing logic of TEST_ASSERT delegates to PRINT instruction, so the issue is in PRINT implementation.

Environment

• morley-1.14.0