Add embedded Docker Mysql to Misk

Spin up Docker image for `MySql:5.7` by default to replace implicit assumption on local MySql instance.

Model after [misk-zookeeper](https://github.com/square/misk/blob/master/misk-zookeeper/src/test/kotlin/misk/clustering/zookeeper/EmbeddedZookeeper.kt) and `vitess/base` Docker use.