[HarfBuzz] Verbose shaping process information

[Olivier Berten]

Hi!

Is there a way to see what Harbuzz is doing step by step in order to
debug font features?

Something like:
Input string: <U+xxxx, U+yyyy, U+zzzz>
Requested features: ss01
Using XXXX engine
Reordering string: <U+xxxx, U+wwww, U+zzzz, U+yyyy>
Switching to glyphs level: <unixxxx, uniwwww, unizzzz, uniyyyy>
Applying 'pref' (1 substitution): <unixxxx, uniwwww, unizzzz_alt, uniyyyy>
etc.

Yours,

Olivier