Update closures lesson

[wvmitchell]

Lesson to be updated: Scope III: Closures

Summary of changes needed:

• This lesson should likely be stand-alone, not part of a 3 part series on scope
• Currently not taught, Closures need to be introduced in M2
• Use this lesson as a starting point, but the closures lesson generally should prepare students to use closures as a data store, and prep them for using functional React components in M3
• Find a place in the M2 calendar for this lesson

Lesson creation guidelines (also on FE Hub

• Lesson Preparation Foundations
• 4 Pillars of Remote Instruction
• Instructional Values
• Culturally Responsive Teaching

[nicktu12]

https://github.com/turingschool/front-end-curriculum/pull/679