Improve MySQL endpoint ping & add mariadb-connector-c

[pgmillon]

• Improve MySQL endpoint ping with custom ports
• add mariadb-connector-c for sha256_password auth
• Update the python code to parse the database url and port in Web and postorius’ docker-entrypoint.sh

[maxking]

Thanks! Ideally, we’d like to keep the two changes as a part of separate PRs so we can reference them properly in changelog generated for release.