[FIXED JENKINS-19872] add configuration options for console output link

This pull request attempts to make the minimum invasive change while still satisfying [#19872][issue]. By default, the user is still presented with a lightbox for the console output, but the user now has the option of selecting 'New Window' or 'This Window' as a link style in the pipeline configuration.

I considered making a `LinkType` or `LinkStyle` enum, but this wouldn't seem to fit in with the rest of the codebase. Instead, the implementation is modeled after the Number of Displayed Items dropdown configuration option.

[issue]: https://issues.jenkins-ci.org/browse/JENKINS-19872