Persist slide numbers and placeholder formatting after generation

[rtyocum]

Change Summary

Previously, after downloading a slide with slide numbers would only show on the slides generated, and not new ones generated by powerpoint, this fixes that

Change Description

Just needed a change of genXml for generating slide masters changing the line that disabled slideNumbers

Change Type

• Bug fix
• New feature
• Documentation update

Motivation and Context

Powerpoints should be editable after the fact, and without this, it makes it more confusing.

Checklist before requesting a review

• My code follows the style guidelines of this project
• My changes generate no new eslint warnings
• I have performed a self-review of my code
• I have commented my code, particularly in hard-to-understand areas
• I have included code/tests that prove my fix is effective or that my feature works
• I have used the "Run All Demos" feature on the browser demo and no errors were found

[rtyocum]

Placeholder formatting after download was also an issue, fixed here as well