Add spreadsheet builder model and specs

[stitching-coder]

Description

Add spreadsheet builder model for bulk update

note: This feature was originally developed by Hudson Molonglo for The New School as a plugin. It has been adapted for the core code of ArchivesSpace.

How Has This Been Tested?

Testing with unit tests

Screenshots (if appropriate):

Types of changes

• 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:

• My code follows the code style of this project.
• My change requires a change to the documentation.
• I have read the CONTRIBUTING document.
• I have authority to submit this code.
• I have added tests to cover my changes.
• All new and existing tests passed.

[stitching-coder]

@thimios I am continuing to work on unit tests.

[thimios]

@stitching-coder I have converted this to a draft PR. Go ahead and click "Ready for review" once you are done with specs and I will review asap.

[thimios]

@stitching-coder looks great, could you squash all commits into one and merge it?

[stitching-coder]

@thimios I do not have permissions to merge it.