Add GaeaNodeResource tests

[BenjaTK]

Adds a few tests to the nodes in the root/ directory:

• That _get_argument_list is overriden.
• That its title isn't "Unnamed"
• That its type is in GaeaValue.Type and that it isn't null.
• That its arguments' types match that same condition.
• That its outputs' types match that same condition.
• That it has outputs.
• That its get_scene return is a valid PackedScene

TO-DO:

• Add non-null type check
• Add non-null argument type check
• Add non-empty description check
• Check that it has outputs
• Check non-null output type
• Check that get_scene is a valid scene.

[Zehir]

I think all tests are needed but there is some improvements on errors message if that possible

[Zehir]

I press the button to run all tests and he updated the file gdunitrunner.cfg

{"included":{"res://testing":[]},"server_port":31002,"skipped":{},"version":"1.0"}

I also removed the file and press the run all tests button and he was able to find all tests.

I am still thinking this file should be gitignored because you define the path inside the yml file for the workflow it's not needed

[BenjaTK]

I press the button to run all tests and he updated the file gdunitrunner.cfg

{"included":{"res://testing":[]},"server_port":31002,"skipped":{},"version":"1.0"}

I also removed the file and press the run all tests button and he was able to find all tests.

I am still thinking this file should be gitignored because you define the path inside the yml file for the workflow it's not needed

gitignored it

[Zehir]

LGTM