test/py: ecdsa: Add test for mkimage ECDSA signing

Add a test to make sure that the ECDSA signatures generated by
mkimage can be verified successfully. pyCryptodomex was chosen as the
crypto library because it integrates much better with python code.
Using openssl would have been unnecessarily painful.

Signed-off-by: Alexandru Gagniuc <mr.nuke.me@gmail.com>
Reviewed-by: Simon Glass <sjg@chromium.org>
1 file changed