This makes a few assumptions for backwards compatibility.
If the facing is not passed to computeShadingParams, the fragment is
assumed to be front-facing.

Replaced alpha layer with base layer.
Areas without RGB blend to the base texture.
Changed blending calculation to a more reliable one.
Blending is now done with interpolation, so transitions are always sharp.
Improved blending used for normal maps.
Added Meta pass.
Reorganised UI to reflect changes.

Apparently POINT_COOKIE is a seperate keyword.

Oops, how embarassing!

This changes all the materials in the scene to use the selected Bakery SH
mode.

At the moment, this shouldn't have any visible effect, but it allows
SPECULAR_AMBIENT_OCCLUSION to be defined locally in the shader, which
opens up the ability to add bent normals to a shader variant.

Add CoreRP-style texture sampling library, to allow for more cross-compatible use of split textures/samplers.

This avoids an issue where dark RTGI over bright baked GI will remove specular.

This implementation is a bit messier and more hackish, but looks much better in motion.

Change exposure occlusion to use the lightmap intensity prior to light being seperated out for lightmap specular.
Previously this was causing artifacts, as the leftover irradiance was extra dark.

Without this it's impossible to define the options needed for parallax sampling in templated shaders.