Add a shared contract test for modules #1576

What happens

Each module tests its own happy path. Behaviour that every module should share is not tested per module, so regressions in it pass every suite:

• starting the same builder twice
• connecting after restart(), when the mapped ports have changed
• withReuse() returning the same container, with the module's setup run once
• a network alias being usable from another container
• cleanup through await using
• non-default credentials actually being applied

Expected

A shared contract test that each module runs against its own container:

describeModuleContract({
  create: () => new RedisContainer(IMAGE),
  connect: async (container) => {
    /* resolves when a client can use the container */
  },
});

Where

• the shared helper in packages/testcontainers/src/utils/test-helper.ts, which modules may already import
• one call in each packages/modules/*/src/*-container.test.ts

Notes

• No new images: each module uses the image it already tests with.
• Some checks will fail on main until the bugs they cover are fixed. Those are the red tests for the fixes.

Dependencies

• Nothing blocks this. It can start now.
• Coordinate with Make start() safe to call more than once on the same container #1520, Call the lifecycle hooks and log consumer when a container is reused #1521: the start-twice and reuse checks are the failing tests for those fixes.