Vulkan: LightmapGI Environment Min Light property not implemented (unlike BakedLightmap in 3.x)

[Calinou]

See also #49935 and #49968.

Godot version

4.0.dev (8747f25)

System information

Fedora 34, GeForce GTX 1080 (NVIDIA 465.31)

Issue description

In the master branch, baked lightmaps cannot have their darkest areas brightened to match a specific color. This is available in 3.x as the Min Light property in the Environment section, which works by max()ing the resulting color in the lightmap (instead of adding to the lightmap, which would result in brightening it everywhere).

Min Light is not physically accurate, but it can be used to avoid overly dark areas in levels. Of course, it should be set to a relatively low value to avoid making lightmaps too dull.

Steps to reproduce

Look for a environment_min_light property in the master branch's LightmapGI node.

Minimal reproduction project

N/A