python3-cryptography: move from meta-python

* inherit new setuptools_rust class (which inherits new pyo3 class, which
  inherits cargo and python3-dir).
* RDEPENDS on python3-pytest-subtests for ptest
* Copy pyproject.toml for ptest as it defines the pytest.marker(s) needed
* Use 'cargo bitbake' to generate the crate:// SRC_URIs
   - Needed some hacks to the Cargo.toml in src/rust/ to make this work (probably
     only package.repository was strictly required):

     [package]
     description = "cryptography includes both high level recipes and low level interfaces to common cryptographic algorithms such as symmetric ciphers, message digests, and key derivation functions."
     homepage = "https://github.com/pyca/cryptography"
     repository = "https://github.com/pyca/cryptography"

* Add patches to src/rust/Cargo.toml to fix cargo errors including  pem version
* Add check-memfree.py to ptest to check for sufficient free memory

(From OE-Core rev: 27bd134c899d00d93806ecb0a62ec3f30b1e6ec6)

Signed-off-by: Tim Orling <tim.orling@konsulko.com>
Signed-off-by: Richard Purdie <richard.purdie@linuxfoundation.org>

meta/recipes-devtools/python/python3-cryptography/run-ptest

@@ -0,0 +1,4 @@
+#!/bin/sh
+if ./check-memfree.py; then
+    pytest -vvvv tests/
+fi