get_certificate - add starttls option with support for mysql

[Ajpantuso]

SUMMARY

Adds a starttls option to allow users to retrieve certificates from MySQL servers.
Fixes #262

ISSUE TYPE

• Feature Pull Request

COMPONENT NAME

plugins/modules/get_certificate.py

ADDITIONAL INFORMATION

• Naïve implementation which does not check for the version/validity of the initial handshake from the MySQL server.

Reference links:

• MySQL
• Openssl Implementation

[Ajpantuso]

@markuman would you be able to try testing this PR locally? I had success with a MySQL server, but would like some more confirmation.

[markuman]

nice @Ajpantuso
works for me. tested against proxysql 2.1.1 and aws rds mariadb 10.4.

[felixfontein]

Thanks for this! Works well :) I've just one small suggestion:

[felixfontein]

@Ajpantuso thanks a lot for implementing this!
@markuman thanks for reviewing and suggesting this!