3d transform tools and grid are affected by environments

[Jummit]

Godot version:
28859e6c2

Issue description:
The 3d viewport transform tools and the grid lines are affected by environments, which makes them look pretty bad in some cases:

Steps to reproduce:

1. Change the default environment, enable bloom for example.
2. Create a 3d scene and select something.

[qarmin]

I'm almost sure, that this is duplicate of other issue.
I have also problem with Light, because it cause, that gizmos are very dark

[clayjohn]

Does this affect GLES2 and GLES3?

[Calinou]

Duplicate of #10478. The underlying cause is the same; this is due to Godot not using render layers for gizmos (which may be possible with the upcoming Vulkan renderer).