Fix for Inspector not running code in @tool scripts until restart

[Hilderin]

This PR should fix the problem where adding @tool in a GDScript where there are getters and setters does not work until the editor is restarted #66381.
I figured out that the problem was caused by creating a PlaceHolderInstance when the script is not a tool and nothing was converting it to a GDScriptInstance when adding @tool. The inverse was probably also a problem when removing the @tool.

It's my first time working with the GDScript, so I certainly missed something especially that my fix was real simple to implement. I did not test extensively.

I did not modify anything to fix the same issue with C# script. I'll wait your feedback before trying the same fix with C#.

• Bugsquad edit: Fixes Inspector not running code in @tool scripts until restart #66381 Fixes @tool functionality doesn't take effect until reloading the project. #95268

[Isabello]

is there any chance this actually makes it into 4.3? This is still a problem in the current beta

[Hilderin]

I modified the code to prevent recalling reload_scripts on itself and fixing a problem where all the scripts received in parameters were reloaded in the loop.

[betalars]

There is now also a MR to document the issue this MR aims to resolve.
Reminder to remove or rephrase that when this gets merged.

[Hilderin]

Just rebased to fix conflicts.

[ryevdokimov]

This needs a rebase, but from initial testing this seems to fix tool scripts from not doing anything at all when first attached until the scene is reloaded. From reading old issues this is something that worked in the past, except for process overrides since those are called on ready.

I have a branch built on top of this one that could be a solution for allowing tool scripts to run as soon as they are attached including the processes: https://github.com/Open-Industry-Project/godot/tree/tool-scripts-without-reloading-scene, ideally leading to a nice workflow of not having to reload the scene as often for testing.