Add mechanism for specifying additional arguments to 'docker run'

[cottsay]

This change adds an escape hatch for passing additional arguments to 'docker run' invocations for release jobs. One possible motivation would be to mount local package repositories into the containers when running release jobs in script mode.

[cottsay]

My first shot at this changed only generate_release_script.py by appending arguments to any line that starts with docker run, but we have some invocations that have bash stuff happening later on the line. Additionally, I think we have to inject the arguments before the label is specified at the end.

[nuclearsandwich]

One possible motivation would be to mount local package repositories into the containers when running release jobs in script mode.

This may require the use of a more specialized configuration to provide mount config for docker-build as well as docker-run since package installation during release jobs happens when building the docker container rather than during docker-run.

[nuclearsandwich]

Does what it says on the tin, although I've left a comment on the proposed example use case as well.

[cottsay]

...to provide mount config for docker-build as well as docker-run since package installation during release jobs happens when building the docker container...

I'm so mad I didn't see this sooner, but you're right. It renders the feature useless to me, so I think we should close the PR. We can always re-open it if we find a use for this functionality.