Fixes CAL-5372
# Delegation Credentials with CalendarCache.
Following content is a snapshot of the [internal document](https://calendso.slack.com/docs/T08B8KA2BNF/F08L5JYU3V3)
**Problem-1 :**
CalendarCache needs SelectedCalendar records to work but SelectedCalendar record is only created when a user connects their calendar and then enables some calendar for conflict checking. Because with Delegation, no manual connection is done by any of the members, we need a way to create SelectedCalendar records automatically.
**Problem-2**
CalendarCache connects to credential(regular credential) which doesn’t exist for Delegation Credential scenario. Also, DelegationCredential is common for all the members(different from Credential which is different for different members) of the organization and we need to identify to which user the CalendarCache belongs.
**Solution for both problems**
- Create credential records for Delegation Credentials as well - Through Cron(new - we could schedule it every 5mins)
- Now create SelectedCalendar records for those Credential records - Through another Cron(new - we could schedule it every 5mins)
- Now CalendarCache records will automatically be created for those SelectedCalendar records -existing cron
## Fixed some Delegation Credentials bugs unrelated to calendar-cache
- If DestinationCalendar wasn't set(which is possible only with Delegation Credentials), then Google Meet wasn't used as a conferencing app - [Added a test]
- If no SelectedCalendar is there but Google Calendar connection exists(possible only with Delegation Credential) then we were not doing conflict checking. It is expected to not do it for Regular Credentials, but for Delegation Credential we must check for conflict in that case too [Added a test]
- Earlier if a user has Regular Credential as well as Delegation Credential for the same external id which is the member email(say member1@acme.com) then availability were retrieved twice because we weren't deduplicating credentials as it wasn't a trivial thing to do. Now that is being done.
**Env Variables:**
Note this PR doesn't introduce any new env variable. The existing env variable has been added to .env.example. But if this env variable isn't already set, it must be set.
`CALCOM_SERVICE_ACCOUNT_ENCRYPTION_KEY={SAME_AS_SET_FOR_V2_API}`
**Deployment Plan:**
1. Add Observability for SelectedCalendar when _error_ field is set
2. Follow https://github.com/calcom/cal.com/blob/calendar-cache-dwd-support/apps/web/app/(use-page-wrapper)/settings/(settings-layout)/organizations/delegation-credential/delegation-credential.md#setting-up-delegation-credential-for-google-calendar-api to enable Delegation Credential for i.cal.com
3. Note that to be able to see the option to enable Delegation Credential for an organization, you need to enable `teamFeature` and `feature` for `delegation-credential`
## Automation Tests
- Introduced tests for calendar-cache.repository.ts
- Tests all methods of the repository
- Added more tests for handleNewBooking/delegation-credential flow.
- Added test to verify the bug fix when no DestinationCalendar exists and Google Meet should be used still
- Added more tests for Google Calendar/CalendarService targeting DelegationCredential
- Added more tests for getCalendarsEvents.
- To test the new logic of calling getAvailability still if there are no selectedCalendars in case of Delegation Credential
- Also introduced tests for `getAvailabitlityWithTimezones` which was an existing function but now has some new changes.
- Added tests for deduplication logic in CalendarManager.ts
## How to Test
Enable Calendar Cache and Delegation Credential feature for acme org through `features` and `teamFeatures` tables.
- Enable Delegation Credential for acme org
- Enable atleast 1 calendar for conflict checking for one of the users(say owner1)
- Ensure GOOGLE_WEBHOOK_TOKEN is set in .env file
- Ensure GOOGLE_WEBHOOK_URL is set to ngrok url of webapp in .env file
- Hit cron endpoint `curl http://localhost:3000/api/calendar-cache/cron\?apiKey\={API_KEY}` that would cache the freebusy result for the selected calendars
Followup
- https://github.com/calcom/cal.com/pull/20698
- https://github.com/calcom/cal.com/pull/18619/files#r2046795643
Found via `codespell -q 3 -S "*.svg,./apps/web/public/static/locales,./packages/app-store/stripepayment/lib/currencyOptions.ts,./packages/lib/freeEmailDomainCheck/freeEmailDomains.ts" -L afterall,atleast,datea,fo,incase,ist,nam,notin,optionel,perview,reccuring`
Closes#19219
