Fixes https://github.com/spring-projects/spring-integration/issues/3804
Instead of manual SMB server setup and preparation, make it all
automated using convenient Testcontainers library and a bit of extra
code executed before tests.
* Change `localhost` to `127.0.0.1` for a proper integration with docker container
* A few new config values to support container environment, like tmpFs,
share permissions and a dynamic port value
* Introduce Testcontainers API for container management
* Few configuration changes to support docker container usage
* Automatic dirs and files layout creation in `@BeforeAll`
* A few bugfixes where the assertion has not been done actually
* Couple of small changes related to assertions readability as well
* Use `warn` as default logging level for the SMB tests
* Refactor an `SmbTests` a bit: moving its `createFilesInSmbShare()` to
the `SmbTestSupport` since that files tree can be useful for any other
similar integration tests in the future
* Use `TestUtils.applySystemFileSeparator()` for cross-platform file paths
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