[3.x] Fix parsing 'preload': increase/decrease parenthesis count

[kdiduk]

This PR fixes #52499. The fix is very simple and safe - we just skip newline tokens if we encounter them after the '(' and before the ')'.
This fix is intended only for 3.4 version. The version 4.0 doesn't have this problem since all the parsing code is rewritten.

[vnen]

I feel like this is not the proper way to go in this case. If you have something like this:

preload(
    "res://"
    +
    "my_resource.tres"
)

It won't work with this fix since it only skip newlines right after the opening parenthesis and before the closing one. I know it's a weird construct but functions allow newlines anywhere in the argument expression, so preload should do the same.

A way to solve this would be to just increment and decrement the parenthesis variable like it's done when finding parentheses in the expression:

godot/modules/gdscript/gdscript_parser.cpp

Line 270 in 673612f

parenthesis++;

[akien-mga]

Needs changes as advised by @vnen.

[kdiduk]

I've updated the PR.
@vnen thank you very much for your help!

[akien-mga]

Tested with a weird case, it seems to work well 👍

const enemy_class = preload(
	
	"res://" +
	
	# Hello :)
	
	"enemies/enemy.gd"
	# Hi!
	)

[akien-mga]

Thanks!