Updates to: Reflections (no longer a Grad Requirement), New DEI lesson, Reordering of DEI lessons, Reorganization of Repo

This PR:

removes mentions that DEI reflective assignments are a graduation requirement.
moves the "DEI Reflective Assignments" introductory lesson to the "Getting Started with Epicodus" pre-work in the Intro curriculum.
creates a new reflection prompt for the new "Social Identities" lesson.
adds a new "Social Identities" DEI lesson.
reorders the DEI lessons for the Intro course, including updating layouts and file names:
- Social Identities is in Section 1 Git, HTML, CSS
- Microaggressions is in Section 2 JavaScript and jQuery
- Equity Vs Equality is in Section 3, Arrays and Looping
moves "Intro to DEI curriculum" lesson and reflection prompt to the not-in-use/ directory
updates content in "Microaggressions" and "Equity Vs Equality" lessons
adds new dei-workshops/ directory that will contain (in the future) short summaries of the DEI workshops
adds new dei-about-the-curriculum/ directory that has a layout file for a new section on LHTP.com/track/diversity-equity-and-inclusion-curriculum

epicodus-classroom / dei-curriculum