Support MySQL 8

[rnorth]

Fixes #736
Replaces #1168

Note that this PR includes some long overdue refactoring of the database container tests - it made sense to do this as I was adding another test class, and doing so without refactoring would have worsened duplication.

The actual substance of the change is quite small, and visible in the MySQLContainer class.

Quoting the rationale:

Testcontainers has the driver as a runtime dependency, not transitive, so it's completely up to the user to choose which driver they need.

I've just tried this out, modifying our jdbc tests to use the newer driver, and found a few things:

The v8 driver seems to be backwards compatible (as you'd hope!) with 5.5, 5.6, 5.7.
With the v8 driver, MySqlContainer still chokes when connecting to mysql:8, throwing SQLNonTransientConnectionException: Public Key Retrieval is not allowed

However, this can be fixed by adding allowPublicKeyRetrieval=true to the query string params, as we already do with useSSL=false.

The allowPublicKeyRetrieval option goes back as far as MySql 5.1, (which predates Docker Hub) and seems to be compatible with any pre-8 image that we'd want to test.

Thus, I now have the following test code working without problems:

for (String tag : asList("5.5", "5.6", "5.7", "8")) {
    try (final MySQLContainer container = new MySQLContainer<>("mysql:" + tag)) {
         container.start();
    }
}

[rnorth]

This is to match the changes mentioned here

For Connector/J 8.0.13 and later:

When UTF-8 is used for characterEncoding in the connection string, it maps to the MySQL character set name utf8mb4.

[rnorth]

This is the main substance of this change.

[kiview]

LGTM, thanks for extracting AbstractContainerDatabaseTest class also.

[rnorth]

Thanks @kiview - will merge!

[rui-ferreira]

When will you publish a release with this?

[rnorth]

This was released in 1.11.4 🎉