feat(uptime): Add uptime monitor count endpoint

[malwilley]

Similar to #92574, but for uptime monitors

[codecov]

Codecov Report

Attention: Patch coverage is 94.44444% with 3 lines in your changes missing coverage. Please review.

✅ All tests successful. No failed tests found.

Files with missing lines	Patch %	Lines
...endpoints/organization_uptime_alert_index_count.py	92.85%	2 Missing ⚠️
...tors/endpoints/organization_monitor_index_count.py	0.00%	1 Missing ⚠️

Additional details and impacted files

@@           Coverage Diff            @@
##           master   #92583    +/-   ##
========================================
  Coverage   87.89%   87.89%            
========================================
  Files       10239    10241     +2     
  Lines      587082   587222   +140     
  Branches    22806    22806            
========================================
+ Hits       515998   516129   +131     
- Misses      70658    70667     +9     
  Partials      426      426            

[evanpurkhiser]

Could you actually have this pull from the Detector model instead? Here's where we create those from project subs

sentry/src/sentry/uptime/models.py

Lines 401 to 412 in ad75d51

	detector = Detector.objects.create(
	type=GROUP_TYPE_UPTIME_DOMAIN_CHECK_FAILURE,
	project=project_sub.project,
	name=project_sub.name,
	owner_user_id=project_sub.owner_user_id,
	owner_team_id=project_sub.owner_team_id,
	config={
	"environment": env,
	"mode": project_sub.mode,
	},
	workflow_condition_group=condition_group,
	)

[malwilley]

Yup! Changed to check that instead