🐛 Fixed 'comped' flag behavior in Member API

[naz]

closes https://github.com/TryGhost/Team/issues/1674
refs TryGhost/Members#407

• The comped flag in Members API unintentionally stopped working when v3 API was dropped with the release of Ghost v5. The flag is deprecated but should be back-compatible for now - we don't want to break integrations like Zapier.
• To properly deprecate the flag we need to plan it's removal and start signalling about it through the version headers

@allouis @SimonBackx marking you for the review as this change has triggered quite a few rewrites in the member test snapshots. The most unexpected one is the format change in the MemberPaidSubscriptionEvent event test. The rest seems like an expected change. It's the territory I have not touched in a long while, so would be great to get 2x:eyes: over the change :pray:

[codecov]

Codecov Report

Merging #15030 (9d103fb) into main (de23ddb) will increase coverage by 0.02%.
The diff coverage is n/a.

@@            Coverage Diff             @@
##             main   #15030      +/-   ##
==========================================
+ Coverage   61.07%   61.09%   +0.02%     
==========================================
  Files         593      596       +3     
  Lines       47557    47649      +92     
  Branches     4271     4290      +19     
==========================================
+ Hits        29044    29112      +68     
- Misses      18464    18488      +24     
  Partials       49       49              

Impacted Files	Coverage Δ
...er/api/endpoints/utils/serializers/output/index.js	58.77% <0.00%> (-0.49%)	⬇️
core/server/web/members/app.js	0.00% <0.00%> (ø)
core/frontend/web/middleware/cors.js	0.00% <0.00%> (ø)
core/server/web/api/middleware/cors.js	100.00% <0.00%> (ø)
...ndpoints/utils/serializers/output/mappers/index.js	100.00% <0.00%> (ø)
...r/api/endpoints/utils/serializers/output/offers.js
core/frontend/helpers/total_paid_members.js	62.50% <0.00%> (ø)
core/frontend/utils/member-count.js	88.00% <0.00%> (ø)
core/frontend/helpers/total_members.js	64.70% <0.00%> (ø)
...dpoints/utils/serializers/output/mappers/offers.js	14.28% <0.00%> (ø)

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[SimonBackx]

The issue with MemberPaidSubscriptionEvent was that we had two Stripe Subscriptions with the same ID. This wasn't an issue in the past, because the subscription was ignored while the comped flag was removed. Now that started to cause some issues internally in the second test (because the subscription already existed and didn't change, so it didn't need to create the MemberPaidSubscriptionEvent). By using a new subscription id, it now creates a new subscription internally and also a new MemberPaidSubscriptionEvent.

+ I also bumped package.json to test this locally

[allouis]

Thanks @SimonBackx for sorting the tests!