[ENG-3520] Remove Quickfiles Code

[Johnetordoff]

Purpose

Remove remaining vestigial quickfiles code that was started in this PR.

Changes

• removes words quickfiles from comments and docs
• removes logical checks for quickfiles
• removes QuickFilesSerializer and QuickFilesDetailSerializer
• removes v2 UserQuickFiles view
• removes osf/management/commands/fix_quickfiles_waterbutler_logs.py, osf/management/commands/reindex_quickfiles.py, osf/management/commands/transfer_quickfiles_to_projects.py
• add conditional migration completely removing quickfiles.

QA Notes

Please make verification statements inspired by your code and what your code touches.

• Verify
• Verify

What are the areas of risk?

Any concerns/considerations/questions that development raised?

Documentation

Side Effects

Ticket

https://openscience.atlassian.net/browse/ENG-3520