[PM-19180] Calculate sales tax correctly for sponsored plans

[jonashendrickx]

🎟️ Tracking

https://bitwarden.atlassian.net/browse/PM-19180

📔 Objective

Sponsored organizations are created in two steps. The sponsorship is the second step where the familiy organization is converted into a family for enterprise organization which is free. Given how the code is otherwise written in the backend related to sponsorships, this proves rather challenging.

We also know we will still need to continue to charge sales tax correctly if the user buys additional storage. And we need to use the PlanType to correctly determine whether the product is for personal use or business use to apply to correct automatic tax rules in Stripe.

Related: bitwarden/clients#14129

📸 Screenshots

⏰ Reminders before review

• Contributor guidelines followed
• All formatters and local linters executed and passed
• Written new unit and / or integration tests where applicable
• Protected functional changes with optionality (feature flags)
• Used internationalization (i18n) for all UI strings
• CI builds passed
• Communicated to DevOps any deployment requirements
• Updated any necessary documentation (Confluence, contributing docs) or informed the documentation team

🦮 Reviewer guidelines

• 👍 (:+1:) or similar for great changes
• 📝 (:memo:) or ℹ️ (:information_source:) for notes or general info
• ❓ (:question:) for questions
• 🤔 (:thinking:) or 💭 (:thought_balloon:) for more open inquiry that's not quite a confirmed issue and could potentially benefit from discussion
• 🎨 (:art:) for suggestions / improvements
• ❌ (:x:) or ⚠️ (:warning:) for more significant problems or concerns needing attention
• 🌱 (:seedling:) or ♻️ (:recycle:) for future improvements or indications of technical debt
• ⛏ (:pick:) for minor or nitpick changes

[github-actions]

Checkmarx One – Scan Summary & Details – 89c455ea-9480-41d8-8218-0517b63b21ce

Great job, no security vulnerabilities found in this Pull Request

[codecov]

Codecov Report

Attention: Patch coverage is 31.25000% with 22 lines in your changes missing coverage. Please review.

Project coverage is 45.25%. Comparing base (39ac933) to head (ee62a21).

Files with missing lines	Patch %	Lines
...e/Services/Implementations/StripePaymentService.cs	29.03%	20 Missing and 2 partials ⚠️

Additional details and impacted files

@@            Coverage Diff             @@
##             main    #5611      +/-   ##
==========================================
+ Coverage   45.12%   45.25%   +0.13%     
==========================================
  Files        1565     1565              
  Lines       71719    71722       +3     
  Branches     6424     6425       +1     
==========================================
+ Hits        32363    32461      +98     
+ Misses      37979    37878     -101     
- Partials     1377     1383       +6     

☔ View full report in Codecov by Sentry.
📢 Have feedback on the report? Share it here.

🚀 New features to boost your workflow:

• ❄️ Test Analytics: Detect flaky tests, report on failures, and find test suite problems.
• 📦 JS Bundle Analysis: Save yourself from yourself by tracking and limiting bundle sizes in JS merges.

[sonarqubecloud]

Quality Gate passed

Issues
0 New issues
0 Accepted issues

Measures
0 Security Hotspots
0.0% Coverage on New Code
11.1% Duplication on New Code

See analysis details on SonarQube Cloud

[cyprain-okeke]

Looks Good