Provide in-network connection details from modules #1567

What happens

Module getters return the address as seen from the test process: the Docker host and a mapped port. A second container on the same Docker network needs a different address, the first container's network alias and its internal port, and no module provides it.

const db = await new PostgreSqlContainer(image).withNetwork(network).withNetworkAliases("db").start();

db.getConnectionUri(); // postgres://test:test@localhost:55012/test, no use to another container

const app = await new GenericContainer(appImage)
  .withNetwork(network)
  .withEnvironment({ DATABASE_URL: "postgres://test:test@db:5432/test" }) // assembled by hand
  .start();

The module knows the internal port, the credentials and the database name. The user has to repeat all of them, and keep them in step with the module's defaults.

Expected

Each module can produce its connection details for use inside a network:

db.getConnectionUri({ network }); // postgres://test:test@db:5432/test

A started container can report its aliases on a network, which this needs.

Where

• packages/testcontainers/src/test-container.ts and started-generic-container.ts, for the aliases
• the connection getters in packages/modules/*/src

Notes

• Kafka and Redpanda already have to deal with in-network listeners. Their approach is a starting point.
• The naming should follow whatever the modules converge on for connection getters.

Dependencies

• Blocked by Take network aliases with the network, and allow more than one network #1536: needs a started container to know its aliases on a network.
• Coordinate with Converge connection getter and command helper names across modules #1538: for the getter name.