Support use of timeout command in Action:run_cmd

Closes: #205 - Implement support for kill_after which uses
timeout with max_end_time but adds an explicit kill signal
if the process does not end.

Signed-off-by: Neil Williams <neil.williams@linaro.org>
15 jobs for killafter in 8 minutes and 50 seconds (queued for 2 seconds)
latest
Status Job ID Name Coverage
  Test
passed #28248
amd64
dispatcher-debian-10

00:02:49

passed #28246
amd64
dispatcher-debian-9

00:03:02

passed #28249
amd64
server-debian-10

00:02:00

passed #28247
amd64
server-debian-9

00:02:30

 
  Analyze
passed #28250
amd64
black

00:00:27

passed #28252
amd64
code_quality

00:00:21

passed #28251
amd64
codestyle

00:00:32

passed #28255
amd64
job-schema

00:00:39

passed #28253
amd64
pylint

00:02:11

passed #28254
dind amd64 allowed to fail
sast

00:01:44

 
  Build
passed #28258
amd64
amd64/pkg-debian-10

00:01:24

passed #28257
amd64
amd64/pkg-debian-9

00:01:28

passed #28256
amd64
doc

00:01:06

 
  Docker
passed #28259
dind amd64
amd64/lava-dispatcher

00:00:41

passed #28260
dind amd64
amd64/lava-server

00:02:07