WIP: start converting user management views' tests to pytest format

[rebeccacremona]

This work was started during the Q3 housekeeping cycle, but was not finished.

Still to do:

• test_org_export_user_list
• test_sponsored_user_export_user_list
• test_create_and_delete_user
• All the tests in "### ADDING NEW USERS TO ORGANIZATIONS ###"
• All the tests in "### ADDING EXISTING USERS TO ORGANIZATIONS ###"
• All the tests in "### VOLUNTARILY LEAVING ORGANIZATIONS ###"
• All the tests in "### REMOVING USERS FROM ORGANIZATIONS ###"
• All the tests in "### ADDING NEW USERS TO REGISTRARS AS SPONSORED USERS ###"
• All the tests in "### ADDING EXISTING USERS TO REGISTRARS AS SPONSORED USERS ###"
• All the tests in "### TOGGLING THE STATUS OF SPONSORSHIPS ###"
• All the tests in "### ADDING NEW USERS TO REGISTRARS AS REGISTRAR USERS) ###"
• All the tests in "### ADDING EXISTING USERS TO REGISTRARS ###"
• All the tests in "### REMOVING REGISTRAR USERS FROM REGISTRARS ###"
• All the tests in "### ADDING NEW USERS AS ADMINS ###"
• All the tests in "### ADDING EXISTING USERS AS ADMINS ###"
• All the tests in "### REMOVING USERS AS ADMINS ###"

Not in scope:

• Any tests of filters: those are going to be a pain to convert, as long as JSON fixtures are still being installed.
• "### SIGNUP" (should be their own file)
• "### PASSWORD RESETS ###" (should be elsewhere)

[codecov]

Codecov Report

Attention: Patch coverage is 69.23077% with 4 lines in your changes missing coverage. Please review.

Project coverage is 69.73%. Comparing base (589f291) to head (b934d0b).
Report is 1 commits behind head on develop.

Files with missing lines	Patch %	Lines
perma_web/conftest.py	69.23%	4 Missing ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##           develop    #3621      +/-   ##
===========================================
- Coverage    69.73%   69.73%   -0.01%     
===========================================
  Files           54       54              
  Lines         7326     7338      +12     
===========================================
+ Hits          5109     5117       +8     
- Misses        2217     2221       +4     

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