Allow fixing indirect missing dependencies manually

[timothyqiu]

Currently, the dependency error dialog is only shown for missing dependencies that are referenced directly by the opening scene. Therefore, if the missing dependency is deeply nested, manually fixing it becomes cumbersome. I guess this is the main reason we devote to improving automatic solutions. However, there are situations where manual fixing is inevitable.

This PR lists all missing items related to the current scene in the Dependency Errors dialog. It also allows the user to open the corresponding dependency editing dialog directly from this dialog, so that they don't have to manually locate them one by one in the file system.

deps-demo.mp4

Note: Ideally, fixing one missing resource should ideally fix all references to it automatically. However, this would involve a complete refactoring of the dependency editing dialog. I think that could be a separate PR.

Test project with several missing dependencies: deps-mrp.zip

Closes godotengine/godot-proposals#12681

[KoBeWi]

Resource name seems to be getting disproportionately more space.

The ratio should be reversed.

[timothyqiu]

Resource name seems to be getting disproportionately more space.
The ratio should be reversed.

It's been using this ratio since 4.0 😆

Updated & changed the ratio to 1:1, so it's the same as 3.x.

I guess this also shows the need for being able to set a special ellipsis position for paths: godotengine/godot-proposals#9598

[timothyqiu]

Rebased to latest master, solving conflicts reported by GitHub.

[KoBeWi]

Superseded by #112187