[macOS] OS::create_process is not passing command line arguments correctly.

[bruvzg]

Godot version:
master, 7f8ab37

OS/device including version:
macOS 11.1

Issue description:
Project Manager is no longer opening projects, since command line arguments are not passed to the editor child process correctly. Opening project fails with the following log (and open another instance of project manager instead), arguments contain random garbage:

Editing project: /Users/bruv/Documents/__godot_control_test_projects/fff (::Users::bruv::Documents::__godot_control_test_projects::fff)
arguments
0: P�U��
1:
2: P�U��
3:
Current path: /Users/bruv/Documents/godot
Unicode parsing error: invalid skip at 1. Is the string valid UTF-8?

Regression from #44514

Steps to reproduce:
Open new or existing project from project manager.

[bruvzg]

Issue is caused by removing this part:

		Vector<CharString> cs;
		cs.push_back(p_path.utf8());
		for (int i = 0; i < p_arguments.size(); i++) {
			cs.push_back(p_arguments[i].utf8());
		}

New code is freeing CharString created by utf8 and making char* ptr invalid on each iteration:

		for (int i = 0; i < p_arguments.size(); i++) {
			args.push_back((char *)p_arguments[i].utf8().get_data());
		}