Add s3mock container

[abhiaagarwal]

Feature request description

With localstack requiring a sign-in (#465), s3mock has emerged as the alternative in both the java and node testcontainers modules (see: testcontainers/testcontainers-node#1169). This provides a way to integration test s3.

Image reference

Github: https://github.com/adobe/S3Mock
Docker: https://hub.docker.com/r/adobe/s3mock

[mervyn-mccreight]

Sounds like a good idea!
PRs are very welcome :)

There is also a fakecloud (see #467) feature in place, but IMO it's okay to have multiple options where users can choose from.

[d-ibanescu]

hi! first pr, i was going to make a moto image but saw this issue open and realized S3mock is a much better option for my own use case.