Highlight scripts used by current scene

[aXu-AP]

Closes godotengine/godot-proposals#10750

[Mickeon]

I see overwhelming positivity behind this PR (not the proposal though). Perhaps it's worth continuing.

Although, we're still struggling to find a good, non-hardcoded theme colour for it. Current PR uses transparency for a dimmer look, but I don't know if that'll play nice on light themes.
Perhaps it could be the theme's highlight colour, but heavily mixed with the theme's background colour used by the list.

[aXu-AP]

Transparency isn't only for dimmer look, it also is needed for regular highlighting to work (it seems that item background is drawn on top of highlight box).
Here's highlight color with transparency down to 20%, various themes:

ai_component is the script selected, mouse is hovering over player. enemy and health_component are in the current scene.
Looks not bad in the default theme. In light theme, the color is quite close to mouse hover color. In black theme highlight is quite dim.
I think it's acceptable? I'm not too worried about being close to hover color. In motion it looks better.

[Calinou]

Current PR uses transparency for a dimmer look, but I don't know if that'll play nice on light themes.

You can use a transparent gray (Color(0.5, 0.5, 0.5, 0.1)) which will work well on any background color. It's fine to hardcode this one as it generally does not need to be ever changed, and is often specific to certain use cases.

[Mickeon]

I like the chosen look in the above screenshots, actually. I am concerned that the background on the fully black theme being completely invisible, though.

Having it be subtle but noticeable is nice. As you said, it looks better in motion. It pops out when changing scenes around but it's not distracting.

A friend has also expressed concern since this is restoring a feature users have gotten used to without. I believe most would see this as an upgrade, but it may warrant an Editor Setting, we'll see.

[aXu-AP]

Here's with transparent gray as suggested by @Calinou:

I think it's tad more readable. Of course it wouldn't work if you have background color of 50% gray, but that's quite rare, and none of default themes do this. Ableton Live is only program that comes to mind that has such color palette.
Editor setting sounds reasonable, as we have it with script temperature also. Some do like more vanilla list.

[aXu-AP]

Changed the color to Color(.5, .5, .5, .1) and added editor setting text_editor/script_list/highlight_scene_scripts now.

[Mickeon]

I'd say yeah as is. It's either this, or the feature is stripped out of the codebase because it currently is not working.

I have a gut feeling that the highlight will miss some scripts in the current scene, but we'll see. There's a huge desire to rework the script list someday, but that day is not as of writing this.

[Calinou]

Tested locally, it works as expected. Built-in scripts work, as well as scripts from instanced subscenes (they will be highlighted as being part of the current scene, which is technically valid).

The highlighting is a bit too subtle for me to easily notice it though. I suggest increasing the opacity to 0.125.

[aXu-AP]

Changed it to 0.125, I think it's about right. Comparison with varying degrees of opacity:

[Calinou]

Looks great!

[Repiteo]

Thanks!