AsdfFile instances cannot be deepcopied

[braingram]

Calling deepcopy on an AsdfFile instance raises an error:

import asdf, copy

af = asdf.AsdfFile()
copy.deepcopy(af)

TypeError: AsdfFile.copy() takes 1 positional argument but 2 were given

asdf/asdf/_asdf.py

Lines 493 to 500 in c1cb054

	def copy(self) -> AsdfFile:
	return self.__class__(
	copy.deepcopy(self._tree),
	self._blocks._uri,
	self._user_extensions,
	)
	__copy__ = __deepcopy__ = copy

doesn't handle memo.

[braingram]

Also copying an AsdfFile loaded from a file with lazy_tree, closing the instance then accessing the copy can produce an error:

import asdf, numpy as np
asdf.dump({"arrs": [np.arange(3) for _ in range(3)]}, "arrays.asdf")
af = asdf.open("arrays.asdf", lazy_tree=True)
af2 = af.copy()
af.close()
af2["arrs"][1][:]

produces an error:

OSError: Attempt to load block from closed file

This might be a separate issue but depending how copy is addressed it might also be fixed with this one.