Add coloring for completion of vector components

[Chaosus]

This is an editor enhancement, which adds a theme colour override for completion items of vector components.

GDScript editor:

Shader editor:

[Riteo]

OMG that's so pretty!

I wonder though, does this happen for other completions? Could it happen for other completions?

Also, I wonder if this fancy feature could be toggled off, just in case it might give problems for some people, which is what I fear it might do for e.g. accessibility reasons, dunno.

[Chaosus]

I wonder though, does this happen for other completions? Could it happen for other completions?

I think yes, but for which? What do you suggest? (This could be added in the future PR).

Also, I wonder if this fancy feature could be toggled off, just in case it might give problems for some people, which is what I fear it might do for e.g. accessibility reasons, dunno.

Thanks for remind this, I've added the flag to disable this feature:

[Riteo]

@Chaosus

I think yes, but for which? What do you suggest? (This could be added in the future PR).

Not sure but I guess that we could see that later as this would already probably cover most of the usecase of this feature.

[Calinou]

Tested locally, it works as expected:

Tested types (excluding compound types that include Vectors as part of their properties): Vector2, Vector2i, Vector3, Vector3i, Vector4, Vector4i, Basis

Note that a script property (or subclass property) called x, y, z or w will not be colored.

[YuriSizov]

LGTM

[akien-mga]

Thanks!