feat: add archiving users

[amcsz]

Closes #1815

Proposed changes

• Add feature to archive users
  • There is a new field in the user model called "user_archived"
  • The field is_active will return false is user_archived is true
• Added management command to archive users based on JSON file
  • Wrote testcases for this
• Added Django admin command to archive users
  • Also wrote testcases for this

Brief description of rationale

[amcsz]

this is also a really rough draft, changes will probably be needed to made later to make sure archived users don't show up in search

[coveralls]

coverage: 79.537% (+0.1%) from 79.398%
when pulling d48b9c5 on amcsz:dev
into aacf793 on tjcsl:dev.