bpo-33975: Avoid small type when running IDLE's htests. (GH-7944)

Import pyshell first in htest to call SetProcessDpiAwareness on Windows
before tkinter.Tk() is called for the htest. Apparently, 'root.destroy()'
undoes a previous 'root = Tk()'. Since IDLE unittests always destroy roots,
a unittest before an htest does not require anything more to work right.
Since part of the purpose of human-viewed tests is to determine that
widgets look right, it is important that they look the same for testing
as when running IDLE.