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/0002-Cargo.toml-edition-2018-2021.patch

@@ -0,0 +1,28 @@
+From 4b73298b214a5b69ea6edf3c2e21dd82b2b29708 Mon Sep 17 00:00:00 2001
+From: Tim Orling <tim.orling@konsulko.com>
+Date: Fri, 14 Jan 2022 22:34:59 -0800
+Subject: [PATCH 2/2] Cargo.toml: edition 2018 -> 2021
+
+Upstream-Status: Pending
+
+Signed-off-by: Tim Orling <tim.orling@konsulko.com>
+---
+ src/rust/Cargo.toml | 2 +-
+ 1 file changed, 1 insertion(+), 1 deletion(-)
+
+diff --git a/src/rust/Cargo.toml b/src/rust/Cargo.toml
+index 174eaa80..7ad053d9 100644
+--- a/src/rust/Cargo.toml
++++ b/src/rust/Cargo.toml
+@@ -2,7 +2,7 @@
+ name = "cryptography-rust"
+ version = "0.1.0"
+ authors = ["The cryptography developers <cryptography-dev@python.org>"]
+-edition = "2018"
++edition = "2021"
+ publish = false
+ 
+ [dependencies]
+-- 
+2.30.2
+