[Enhancement]: make execInContainer asynchronous

Module

Core

Proposal

In function org.testcontainers.containers.ExecInContainerPattern#execInContainer(com.github.dockerjava.api.DockerClient, com.github.dockerjava.api.command.InspectContainerResponse, java.nio.charset.Charset, java.lang.String...)

I found this part of code:

        try (FrameConsumerResultCallback callback = new FrameConsumerResultCallback()) {
            callback.addConsumer(OutputFrame.OutputType.STDOUT, stdoutConsumer);
            callback.addConsumer(OutputFrame.OutputType.STDERR, stderrConsumer);

            dockerClient.execStartCmd(execCreateCmdResponse.getId()).exec(callback).awaitCompletion();
        }

It seems like this part of code is producing the result in a synchronous and blocking pattern.

This seems to have the impact on the logging and makes it impossible to see the logs as they arrive.

Is it possible to make this asynchronous?

Start with org.testcontainers.containers.ExecInContainerPattern#execInContainer and inspect the shown FrameConsumerResultCallback and execStartCmd flow. Determine how asynchronous execution should expose output as it arrives without blocking, then verify that logging is observable during execution and that the existing execution result behavior remains covered.