Remove default images and versions from modules

[cristianrgreco]

We currently have default images and versions defined for all modules. This means users can start a container effortlessly like new PostgreSqlContainer().start(). This works well when the module is first created and is using the latest versions, but as these versions get out of date, it is not possible for Testcontainers to push a change increasing the default module versions, as it could potentially break the builds of everyone using the default values. It is not feasible to continuously update and push out breaking changes.

The change will simply make the image name and version mandatory, e.g new PostgreSqlContainer("postgres:X.Y.Z").start().

[joebowbeer]

NOTE to check/update the installation examples, too:

https://github.com/testcontainers/community-module-registry