Use external mysql 8.0 database with enhanced password encryption

[tsboh]

Description

As a developer I would like to be able to connect from within a Docker container based on this Docker flarum image to a external MySQL database (8.0) with support of the new MySQL 8 default password encryption.

At this point in time I'm able to connect to that same database using the Legacy password encryption (mysql_native_password) for a user on the MySQL 8 database . So that works. So it's possible to run the forum with this image with an external database.

The feature request is to add the new MySQL 8 default password encryption (caching_sha2_password). By installing that plugin from within the Dockerfile. So that I'm able to connect to the external database with the enhanced password encryption (aswell).

Thank you for your time and effort that you already put into this project. I'm a happy user!
Hope you can find the time to enhance the security of the forum installation by adding this feature, thanks.

Cheers