Allow docker in test actions to add capabilities

Unless the container is started with an extra capability, the test
shell cant mount block devices. Allow the job definition to specify
capabilities that are added to the docker command line.

Change-Id: I41a7e94956629e20d9134b103c71ad98180f5f1a
16 jobs for docker-k64f in 16 minutes and 2 seconds (queued for 4 seconds)
latest
Status Job ID Name Coverage
  Test
passed #117718
amd64
dispatcher-debian-10

00:02:22

passed #117720
amd64
dispatcher-debian-11

00:03:08

passed #117719
amd64
server-debian-10

00:03:06

passed #117721
amd64
server-debian-11

00:05:24

 
  Analyze
passed #117722
amd64-dind
bandit-sast

00:00:54

passed #117723
amd64
black

00:00:35

passed #117724
amd64
code_quality

00:00:20

passed #117729
amd64
codespell

00:00:18

passed #117725
amd64
coverage

00:06:28

60.87%
passed #117726
amd64
dockerfiles

00:00:15

passed #117728
amd64
pylint

00:03:04

passed #117727
amd64
schemas

00:00:30

 
  Build
passed #117731
amd64
debian/10

00:01:23

passed #117730
amd64
doc

00:00:38

passed #117732
amd64-dind
docker-amd64-dispatcher

00:03:37

passed #117733
amd64-dind
docker-amd64-server

00:04:06