Start the container from script

[pmatos]

One request of to allow something like the following:
build-jsc.sh --arch mips --container pmatos/jsc-qemu-system-mips32el:latest

[pmatos]

A few other suggestions for enhancements from xan:

• make the FAILED message less ominous when waiting for qemu
  maybe just === 24774: failed... still trying - don't give up on me!
  after 3 tries === 60758: failed again... seriously, consider upgrading your hardware!
  after 5 failures It's dead, Jim
• also for build-jsc.sh I think an option to just go ahead with an existing build dir would be useful; if not the default maybe a -f flag (maybe that could be the default and -f could wipe out the dir)
• I'm thinking what I suggested would be a nicer way of doing things magically? but could work either way; like just git clone your scripts, have a --container parameter that does everything automatically (it could even pull your buildroot if needed)
  and getting into the docker image would be a special case when you need to debug and such?
  just thinking that if you could just do everything for the user without them needed to learn podman/docker in the common cases that would be awesome, basically
  (Maybe build-jsc could, without a buildroot, to pull the docker image and mount the directory inside the container locally for the duration of the build/test. Surely that's possible...)