Document builder class

[vkbo]

Summary:

This is a module of the core functionality needed for building manuscript documents. It is primarily extracted from the current build tool and is intended to be used by both the new build tool and other features that can generate external documents.

Related Issue(s):

Resolves #1314

Reviewer's Checklist:

• The header of all files contain a reference to the repository license
• The overall test coverage is increased or remains the same as before
• All tests are passing
• All flake8 checks are passing and the style guide is followed
• Documentation (as docstrings) is complete and understandable
• Only files that have been actively changed are committed