Make "inspect native shader code" available also when selecting shader resources

[QbieShay]

Describe the project you are working on

Godot engine

Describe the problem or limitation you are having in your project

"Inspect native shader code" is available when inspecting a material, but not when inspecting a shader

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

Make it avialable for shaders too

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

Add the option in the dropdown

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

No

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

Native editor feature

[tetrapod00]

Made a PR: godotengine/godot#97205.