Add different color for unfocused selected editable text

[Zeophlite]

Objective

• Closes Text input should hide text highlighting when focus lost #23889

Solution

• Added unfocused_selection_color: Color to TextCursorStyle

Testing

• cargo run --example multiple_text_inputs

• cargo run --example feathers_gallery --features="experimental_bevy_feathers"

[ickshonpe]

Looks good.

[ickshonpe]

The defaults don't matter too much here, but the blue is a bit too prominent, they should be chosen to suggest which is the focused input. Maybe just same as the selection color but with 0.5 alpha or something.

[alice-i-cecile]

I think we should try and pick decent defaults for all of these colors. I'll make a follow-up once this is in.

[jordanhalase]

Also, could this be invisible rather than a lighter accent color? For HTML inputs the selection turns invisible out of focus by default, and I think more people will expect it that way unless they are writing something like a code editor where they expect to still see their highlighting when clicked off.

I do not feel very strongly about this, but I imagine users would not prefer to see highlighting retained when clicking between many small inconsequential text/number inputs, and to reserve that behavior for larger more "important" text inputs.