[8u] RFR(s): 8221342: [TESTBUG] Generate Dockerfile for docker testing

[Severin Gehwolf]

Hi!

Please review this 8u backport of this test bug which enhances
container testing to automatically generate docker files. This is
useful if the development platform is not Oracle Linux 7.X (which is
the case for me).

The JDK 11 patch applies cleanly (after JDK-8220313 which is in the
approval queue) but doesn't compile since Files.writeString() API is
not available in JDK 8. Replaced it with:

byte[] bytes = dockerFileStr.getBytes(StandardCharsets.UTF_8);        
Files.write(dockerfile, bytes);

The second change needed was to adjust the package name for
DockerfileConfig as there are two sets of container tests: one for
hotspot and one for jdk.

Bug: https://bugs.openjdk.java.net/browse/JDK-8221342
webrev: http://cr.openjdk.java.net/~sgehwolf/webrevs/JDK-8221342/jdk8/01/

Testing: Docker tests with -Djdk.test.docker.image.name and
-Djdk.test.docker.image.version on my F32 which now works. Previously a
manual change of Dockerfile-BasicTest was needed.

Thoughts?

Thanks,
Severin