Add custom config path in default mysql config

[aikfiend]

Allows the using a custom MySQL configuration file to avoid the building of custom images with their own configs.
Probably will require changes in README.md on the docker hub.

[mysql-oca-bot]

Hi, thank you for submitting this pull request. In order to consider your code we need you to sign the Oracle Contribution Agreement (OCA). Please review the details and follow the instructions at https://oca.opensource.oracle.com/
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Thanks

[mysql-oca-bot]

Hi, thank you for your contribution. Please confirm this code is submitted under the terms of the OCA (Oracle's Contribution Agreement) you have previously signed by cutting and pasting the following text as a comment:
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Thanks

[aikfiend]

I confirm the code being submitted is offered under the terms of the OCA, and that I am authorized to contribute it.

[mysql-oca-bot]

Hi, thank you for your contribution. Your code has been assigned to an internal queue. Please follow
bug http://bugs.mysql.com/bug.php?id=106460 for updates.
Thanks

[hagaivcita]

is there any plan to merge this?
that would be very helpful!
currently im making some hacky changes to make the functionality

[aikfiend]

is there any plan to merge this? that would be very helpful! currently im making some hacky changes to make the functionality

I guess you can Subscribe and say Affects me somewhere here:
https://bugs.mysql.com/bug.php?id=106460
but no clue when this feature will be merged