feat(demo-mode): passwordless login

[obostjancic]

• Closes: Automatically log vistors in #79007

Context

• In order to replace Current sandbox, which is a self-hosted instance available at https://try.sentry-demo.com/ we created a SaaS sandbox org https://sandbox.sentry.io/
• Event data in sandbox org will be synced with demo org through sentry-mirror
• In order to allow public access to this org we created a Demo User
  • that should have read-only access to only this org. PoC PR
  • that should be able to log in automatically. WIP PR
• sandbox org and Demo User are behind demo-mode.orgs and demo-mode.users options respectively. Those options are added in PR

[codecov]

Codecov Report

Attention: Patch coverage is 45.16129% with 17 lines in your changes missing coverage. Please review.

✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
src/sentry/utils/demo_mode.py	43.47%	13 Missing ⚠️
src/sentry/web/frontend/auth_login.py	40.00%	3 Missing ⚠️
src/sentry/utils/auth.py	66.66%	1 Missing ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##           master   #83090      +/-   ##
==========================================
+ Coverage   87.57%   87.62%   +0.05%     
==========================================
  Files        9459     9440      -19     
  Lines      536794   536268     -526     
  Branches    21130    21047      -83     
==========================================
- Hits       470086   469898     -188     
+ Misses      66349    66011     -338     
  Partials      359      359              

[constantinius]

I think this check short circuits the check whether the email is in the "demo-mode.users" option. It will return with True whenever it is set to any non-empty string.

[mdtro]

Can you add tests to ensure this all behaves as expected?