Test FragmentShader.setImageSampler memory leaks (Linux and Android simulator)

By running this app, memory leaks start to be noticed after 40~60 seconds on the Operating System Monitor. Memory tab of DevTools doesn't report leaks.

• This sample uses 2 shaders: shader_a.frag and shader_b.frag.
• The shaders are drawn using PictureRecorder() and the output is stored into 2 different ui.Images.
• When pressing the button, the Ticker starts updating shader outputs.
• shader_a uses the lastest output of shader_b as sampler2D uniform and shader_b uses the latest output of itself.

The leak doesn't occurs when:

• Removing the sampler2D uniform from shader_b.frag (and of course the setImageSampler from computeShader2())
• in computeShader2() replace setImageSampler(0, sampler1 ?? blankImage!); with setImageSampler(0, blankImage!); where blankImage is the image loaded at start

Here a screenshot of the System Operating System memory monitor. After about 40 seconds memory leaks start growing till 100% is reached.