[skottie] Defibrillate wipe effects

Since we can't use mask filters on layer paints any longer, refactor the
existing wipe effects to use explicit shader masking:

  - remove SkSG::MaskFilterEffect - it no longer works
  - replace with SkSG::MaskShaderEffect
    - for atomic draws, apply the shader to the draw paint as
      SkShader::Blend(kSrcIn, mask_shader)
    - for isolated content, apply the mask as an extra pass
      drawPaint(kDstIn, mask_shader) before restoring the layer
  - refactor VenetianBlindsEffect, LinearWipeEffect and RadialWipeEffect
    to use mask shaders
  - additionally, refactor the RadialWipeEffect gradient to avoid using
    a local shader matrix (does not compose correctly within the new
    framework)

Everyone clear... do not touch the patient... BZZZT!

TBR=

Change-Id: I3a88da97a17b3b68812480cad5298b8778b6847c
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/275694
Reviewed-by: Florin Malita <fmalita@chromium.org>
Reviewed-by: Michael Ludwig <michaelludwig@google.com>
Commit-Queue: Florin Malita <fmalita@chromium.org>
9 files changed