Check that docker is running when running src batch

[malomarrec]

Current behaviour

If I run a src batch preview, but Docker is not running, I get a not very informative

❌ Error:
   exit status 2

This confuses users, and ... sure you need to RTFM, but that takes time.
It's a very very frequent failure mode in first usage.

Proposed behaviour

Check that docker is running, and fail with an explicit error

Environemnt

MacBook Pro / M1

[Piszmog]

Should consider a helpful message as well, such as Ensure docker is running. The full error message produced may still be confusing to a user.

[adeola-ak]

P2?

[chrispine]

We have a check that apparently isn't working anymore.

[chrispine]

customer ran into this, so moving it back to Triage

[rprince-anduril]

I just ran into this on OSX 12.5 running Docker Desktop 4.3.2

$ src batch preview -f fix-ecr-issues.batch                                                                                                                                 ~/Downloads

❌ Error:
   exit status 1