[Enhancement] Support creating ECC Keys

[schurzi]

Description

Currently we create a RSA 4096 bit key by default. It seems we also provide the possibility to inport an external key. I think we should also support creating ECC keys directly.

Arguably ECC keys are "better" in many regards so maybe we should even change the default.

Additional information

https://github.com/T-Systems-MMS/ansible-collection-acme/blob/6f8124eb085260aba2f63cbeb64643ecc8c62199/roles/acme/tasks/create-keys.yml#L2-L8

[schurzi]

see also https://eff-certbot.readthedocs.io/en/stable/using.html#rsa-and-ecdsa-keys

[schurzi]

BSI Recommends in TR-02102-2:

• brainpoolP256r1
• brainpoolP384r1
• brainpoolP512r1
• secp256r1
• secp384r1
• secp521r1

[rndmh3ro]

We should probably make it configurable but default to secure defaults.