Add support for library resources

[steven-terrana]

PR Details

I ended up fixing some stuff related to building the documentation in this PR.

Adding library resources and changing the library file structure had some rippling changes across the library development documentation.

This caused me to reread the library development documentation and it.. needed some attention. So it was reorganized and more or less rewritten in some places.

fixes #46

Description

Adds support for fetching static assets in a library's resources directory through a resource utility method that's only available within library steps.

Fetching resources in another library is not supported. This is an intentional decision to nudge folks towards the best practice that libraries remain self-contained and to avoid the pitfall of colliding library resource relative paths across libraries.

How Has This Been Tested

Unit Testing
Integration testing with a real jenkins

Types of Changes

• Added Unit Testing
• Docs change / refactoring / dependency upgrade
• Bug fix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that would cause existing functionality to change)

Checklist

• I have added the appropriate label for this PR
• If necessary, I have updated the documentation accordingly.
• All new and existing tests passed.