Better format arguments in variant parser

[YeldhamDev]

Removed extra spaces from the variant parser, which means that in the docs values will appear as Vector2(0, 0) instead of Vector( 0, 0 ).

[akien-mga]

This will have a big impact on the serialization of Variants in tscn and tres files, it breaks compat a priori.

I'm in favor of it but that's 4.0 material, and we need to ensure that the parser can handle both styles (but saves it without extraneous spaces). The current style is likely @reduz's personal preference when he designed it, so we should also discuss it to reach a consensus before changing it.

[akien-mga]

Made arguments in the connection dialog be arg: type instead of type arg,

This could still be merged for 3.2 though.

and removed extra spaces.

And this possibly, as long as only the editor is impacted and we don't consider the discrepancy with serialized values an issue.

[Calinou]

Removed extra spaces from the variant parser, which means that in the docs values will appear as Vector2(0, 0) instead of Vector( 0, 0 ).

From my testing, it ignores whitespace so even the following can be parsed successfully:

Vector2(
	0,
	0
)

The only thing that's not allowed is having trailing commas. Adding support for trailing commas in constructors would allow for better VCS diffs (see #32124).

[YeldhamDev]

The connections dialog changes were moved to the newly created #32357 commit.

[akien-mga]

Code and change look good to me.

For the record, we should probably add more tests for VariantParser (there's two strings in tests/test_config_file.h affected by this PR but that's all, which shows that our coverage for Variant serialization isn't top notch ;)).

[akien-mga]

Thanks!