Drag property with CTRL/SHIFT generates code to get/set the property

[theraot]

This pull request implements and closes: godotengine/godot-proposals#8017

Supercedes #82946

This pull request will allow Godot to:

• Generate code to get value of a property dragged from the inspector while holding CTRL.
• Generate code to set/assign a value of a property dragged from the inspector while holding SHIFT. The value being set will be the default value of the type of property, and it will be automatically selected in the code editor.
• Generating code to access arrays and dictionaries is supported. But generating code for keys containing objects is not supported (this is a toast error). Similarly dropping the labels for a new item is not supported (this is a toast error).
• Generating code to access metadata is supported.
• Fixes dropping metadata generating text prefixed with "metadata/". Now the name of the metadata is dropped.
• Fixes dropping dictionary keys or array indexes prefixes with "indices/". The key or index is dropped if possible, otherwise it is a toast error.
• Bonus: dragging a property from project settings will drop the full property path (the code to get it or set it will not be generated).

[timothyqiu]

One caveat is that node.property is not equvalent to node.get("property"). The former can act as setter too.

[theraot]

Yes. but:

1. I rather not have a call to get if it is not necessary. Which also aligns this with QOL-Enhancement: Dragging properties from inspector into code without "Quotation marks" godot-proposals#8014 in the simple case.
2. It didn't make sense to me to generate an assignment.

Addendum: I believe I could make an assignment/call to set with the current value of the property, but I think that would require to introduce another key modifier. Thus, I'm thinking that if people want that, it could be another proposal and pull request.

[aXu-AP]

Seems to be working well 👍
If you manage to make subresources work, I hope shader parameters get some special attention, as those require the most writing/remembering. Could be a follow up though.
I think for set though, shift modifier could be used. In that case, caret should be moved to before closing bracket. And for the non-quotatable properties it should then add object.property = (of course, it's a bit extra, but it would be logical).