Every docker test results in a series of calls by jtreg:
1. check whether docker demon is running
2. create docker tests image
3. (sanity check) run "java -version" inside docker container
4. ...
<commands which actually test something inside docker image>
N. remove docker test image

Every such command generates stdout and jtreg dumps it in a file. Developers later can open these files to get familiar with stdout from individual command. The problem here is that it's difficult to map individual files to the source [COMMAND] causing it.

With this ticket I would like to extend each STDOUT file with information about the command causing that STDOUT header section.

We can the format in sync with the format of .jtr file where [COMMAND] is followed by [STDOUT]:
Example of such file would be:
```
[COMMAND]
docker run --tty=true --rm jdk8-internal:test /jdk/bin/java -Djdk.test.docker.image.name=ubuntu -Djdk.test.docker.image.version=latest -version
[STDOUT]
java version "1.8.0_361-internal"
Java(TM) SE Runtime Environment (build 1.8.0_361-internal-2022-09-09-1116350.john22...-b00)
Java HotSpot(TM) 64-Bit Server VM (build 25.361-b00, mixed mode)
```