tests: regenerate x509 test certificates
The old x509 test certificates were using cryptographic settings
that are ancient by today's standards, namely 512 bit RSA keys.
To put things in perspective, browsers have been dropping support
for 1024 bit RSA keys.
I think it is important that tests match the realities of the times.
And 2048 bit RSA keys with SHA-2 hashing are what the world is
moving to.
This patch replaces all the x509 certificates with new versions using
modern best practices. In addition, the docs for generating the
keys have been updated, as the existing docs left out a few steps,
namely how to generate certs that were not active yet or expired.
-----BEGIN CERTIFICATE-----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-----END CERTIFICATE-----