Implement distinct stress tests

[frank-weindel]

• stress-single-level (renamed from stress)
  • Animates 100 * multiplier image nodes with the same texture
  • This tests one of the fastest render passes where everything is rendered with a single renderOp and texture bind.
• stress-multi-level
  • Animates 100 * multiplier container nodes each that have a child node with the same texture
  • This tests the case where container nodes wrap an image node, which can result in a renderOp for each node draw and alternating texture binds, if not properly optimized.
• stress-multi-texture
  • Animates 100 * multiplier image nodes with two alternating textures
  • This tests a worst case scenario where a new renderOp and texture bind is needed for each draw call.