oeqa: add simple 'maturin' SDK (testsdk) test case

We expect 'maturin' will be used in SDKs, so it makes sense to also
test it in the testsdk environment.

To run this test case, you can add the following to local.conf:
TOOLCHAIN_HOST_TASK:append = " nativesdk-python3-maturin"

And then build and test the SDK:
bitbake -c populate_sdk core-image-full-cmdline
bitbake -c testsdk core-image-full-cmdline

You can substitute a different image recipe for "core-image-full-cmdline"

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