Fix --plugin-path when running with run command and support default value

[jonesbusy]

By default when running without plugin argument it will use the local directory using implicit --plugin-path . arg.

This would make very easy to run recipes during development or when refreshing a very old plugin (where some action are manual because we cannot do magic).

For example I use this approach on jenkinsci/pipeline-cps-http-plugin#16

Testing done

Automated tests

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