Revert "[rust png] Make `SkTypeface_fontations.cpp` agnostic to PNG decoder"

This reverts commit 9f38e6c6777e64e1f5d351de7283815a9f37af71.

Reason for revert: Need to guard chromium

Bug: chromium:414823091
Original change's description:
> [rust png] Make `SkTypeface_fontations.cpp` agnostic to PNG decoder
>
> Before this CL, Fontations would always use `libpng`-based PNG decoder.
>
> After this CL, clients need to register a png decoder (via
> SkCodecs::Register) before using the font manager.
>
> This also cleans up the FontConfig code, decoupling it
> from FreeType by deprecating the non-explicit API to create
> a FontConfig SkFontMgr.
>
> Bug: chromium:414823091
> Change-Id: Ib5a4c750d857ef01887aa2cc13f6c260bdb92c1d
> Reviewed-on: https://skia-review.googlesource.com/c/skia/+/987597
> Commit-Queue: Kaylee Lubick <kjlubick@google.com>
> Reviewed-by: Ben Wagner <bungeman@google.com>

Bug: chromium:414823091
No-Presubmit: true
No-Tree-Checks: true
No-Try: true
Change-Id: I174f146bbeb7a11f409543266b255006ba296ab5
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/1000516
Owners-Override: Kaylee Lubick <kjlubick@google.com>
Bot-Commit: Rubber Stamper <rubber-stamper@appspot.gserviceaccount.com>
15 files changed