provider/docker: No support for docker run --user options

[lvjp]

Since docker metadata are not supported by packer, it hard to run apps without use of root user.

For that one and others reason, i suggest to introduce a mapping to the docker run --user option

[stack72]

This has been merged in #5300

[ghost]

I'm going to lock this issue because it has been closed for 30 days ⏳. This helps our maintainers find and focus on the active issues.

If you have found a problem that seems similar to this, please open a new issue and complete the issue template so we can capture all the details necessary to investigate further.