Add SampleApp that shows problems in stroking

Add SampleApp that shows problems in stroking

- When the stroke width gets too big the raster algorithm produces
  incorrect output
- This also causes the GPU path to produce incorrect output if the width
  is larger than an arbitrary limit in GrAALinearizingConvexPathRenderer
  (which is the renderer used for this specific geometry)

- Other non-convex geometries probably also produce strange results

BUG=skia:5405,skia:5406
GOLD_TRYBOT_URL= https://gold.skia.org/search?issue=2060903002

Review-Url: https://codereview.chromium.org/2060903002