Remove the need to restart editor when modifying most 3D Gizmos settings

[yahkr]

Describe the project you are working on

Any project

Describe the problem or limitation you are having in your project

Having to restart the editor to change the color/setting of a gizmo

Describe the feature / enhancement and how it helps to overcome the problem or limitation

allow the gizmo settings to be updated on demand

Describe how your proposal will work, with code, pseudo-code, mock-ups, and/or diagrams

refactor constructors to have a update_materials method instead of only creating the gizmo materials once.

If this enhancement will not be used often, can it be worked around with a few lines of script?

not to my knowledge

Is there a reason why this should be core and not an add-on in the asset library?

it affects 3DGizmoPlugin classes