### Godot version

4.0

### System information

Windows 10 x64

### Issue description

We have an established way to inform about invalid input fields: using red/green/yellow labels at the bottom:
![](https://user-images.githubusercontent.com/2223172/235779087-7db4a899-dd41-40c7-8cb3-b295a42eec5e.png)
It's used in Create New Scene dialog, Add Metadata dialog, New Folder dialog, Create Script dialog and probably others.

Meantime the New Plugin dialog (accessible in Project Settings -> Plugins) looks like this:
![image](https://user-images.githubusercontent.com/2223172/235783588-ef5e560c-8620-4017-9b50-86f8477fe40e.png)
Instead of info labels, it uses info icons that show message on hover. This dialog was created before we had an established way of validating input, so it needs updating.

### Steps to reproduce

1. Project
2. Project Settings
3. Plugins
4. Create New Plugin
5. 👀

### Minimal reproduction project

N/A
name_validation->set_tooltip_text("");
	subfolder_validation->set_tooltip_text("");
	script_validation->set_tooltip_text("");
	
	Vector<String> errors;
	if (name_edit->get_text().is_empty()) {
		is_valid = false;
		name_validation->set_texture(invalid_icon);
		name_validation->set_tooltip_text(TTR("Plugin name cannot be blank."));
	}
	if ((!script_edit->get_text().get_extension().is_empty() && script_edit->get_text().get_extension() != ext) || script_edit->get_text().ends_with(".")) {
		is_valid = false;
		script_validation->set_texture(invalid_icon);
		script_validation->set_tooltip_text(vformat(TTR("Script extension must match chosen language extension (.%s)."), ext));
	}
	if (!subfolder_edit->get_text().is_empty() && !subfolder_edit->get_text().is_valid_filename()) {
		is_valid = false;
		subfolder_validation->set_texture(invalid_icon);
		subfolder_validation->set_tooltip_text(TTR("Subfolder name is not a valid folder name."));
	} else {
		String path = "res://addons/" + _get_subfolder();
		if (!_edit_mode && DirAccess::exists(path)) { 
			is_valid = false;
			subfolder_validation->set_texture(invalid_icon);
			subfolder_validation->set_tooltip_text(TTR("Subfolder cannot be one which already exists."));
		}
	}
	get_ok_button()->set_disabled(!is_valid);
}
String PluginConfigDialog::_get_subfolder() {