Schema cleanup and bugfixes

[david-waltermire]

Committer Notes

This set of changes are to cleanup a variety schemas.

• Fixes a bug in the base64 data type that caused by most of the allowed alphabet to be excluded as well as padding characters.
• Corrected duration-based patterns to enforce the correct semantics.
• Simplified boolean patterns.
• Aligned integer and string data type derivations.

All Submissions:

• Have you followed the guidelines in our Contributing document?
• Have you checked to ensure there aren't other open Pull Requests for the same update/change?
• Have you squashed any non-relevant commits and commit messages? [instructions]
• Do all automated CI/CD checks pass?

Changes to Core Features:

• Have you added an explanation of what your changes do and why you'd like us to include them?
• Have you written new tests for your core changes, as applicable?
• Have you included examples of how to use your new feature(s)?
• Have you updated all website](https://pages.nist.gov/metaschema) and readme documentation affected by the changes you made? Changes to the website can be made in the website/content directory of your branch.

[wendellpiez]

Thanks @david-waltermire-nist

[nikitawootten-nist]

A few questions below :)

[aj-stein-nist]

Is it ok I request a rebase against current develop to include #344 to make testing easier? I work around it, but it would be minorly helpful. :-)

[david-waltermire]

Is it ok I request a rebase against current develop to include #344 to make testing easier? I work around it, but it would be minorly helpful. :-)

Done.

[david-waltermire]

I believe this PR is ready to merge. I'll merge it once @nikitawootten-nist approves.