Ensure that "detect 3D" is only called when using 3D shaders

[clayjohn]

Fixes: #62087

In the RD backend p_use_linear_color wasn't being properly sent to update_textures leading it to treat every shader as a 3D shader. This caused two problems:

1. Detect 3D was always called ("Detect 3D" is triggered for ShaderMaterial with shader_type canvas_item; #62087), and
2. When using canvas_item shaders with source_color the texture was converted to srgb twice, leading to it looking bad

In the GLES3 backend we didn't even track if a material was 3D or not, so the plumbing had to be added.

Tagging for 4.1, but not 4.0 as this will introduce a slight behaviour change that users may already be working around.

[akien-mga]

Thanks!