StencilParameters support on WebGPU

[mvaligursky]

• Portal and ScrollView engine examples now work on WebGPU
• StencilParameters file / class was moved from scene to platform/graphics, along BlendState and DepthState, as a data container for the main API allowing stencil parameters setup.
• WebgpuGraphicsDevice now handles stencil buffer on the main framebuffer, specified by the creation options.
• WebglGraphicsDevice construction now handles options.stencil. Before it was hardcoded to true.

new API

	GraphicsDevice.setStencilState(stencilFront, stencilBack);

deprecated API on WebglGraphicsDevice:

• The functionality is still there, but no longer exposed / documented.

	setStencilTest
	setStencilFunc
	setStencilFuncFront
	setStencilFuncBack
	setStencilOperation
	setStencilOperationFront
	setStencilOperationBack

Possible future improvements: #5244