Universal Bugfixes (#6109)

* Fixed shader pass name issue (case 1201696)

* Fixed typo in encodedIrradiance.

* Fixed viewport rect not working with render textures.

* Added changelog

* Enabled Allocations tests when rendering.

* Forward Renderer is not sealed anymore. Now developers can subclass it.

* Added Test Scene

* Excluded post-processing tests from build.

* Enabled playmode tests for all assemblies

* Removed unnecessary new shader. UnlitTexture is used instead.

* Updated reference images.

* Updated scene to fix tests.

Author: phi-lira