[STRATCONN-5489] - Add batch_keys to Klaviyo actions

[varadarajan-tw]

This PR adds a new hidden batch_keys mapping to all Klaviyo actions. This mapping controls how events are batched together.

This PR in itself won't have any effect as it depends on https://github.com/segmentio/integrations-go/pull/449. The integrations-go changes are behind a flagon and we'll be doing a controlled rollout.

Test Doc - here

Testing

• Added unit tests for new functionality
• Tested end-to-end using the local server
• [If destination is already live] Tested for backward compatibility of destination. Note: New required fields are a breaking change.
• [Segmenters] Tested in the staging environment
• [Segmenters] [If applicable for this change] Tested for regression with Hadron.

[codecov]

Codecov Report

Attention: Patch coverage is 61.76471% with 13 lines in your changes missing coverage. Please review.

Project coverage is 77.84%. Comparing base (cf633f8) to head (5094161).
Report is 11 commits behind head on main.

Files with missing lines	Patch %	Lines
...tion-actions/src/destinations/klaviyo/functions.ts	28.57%	8 Missing and 2 partials ⚠️
...src/destinations/klaviyo/subscribeProfile/index.ts	83.33%	0 Missing and 1 partial ⚠️
...c/destinations/klaviyo/unsubscribeProfile/index.ts	83.33%	0 Missing and 1 partial ⚠️
...ns/src/destinations/klaviyo/upsertProfile/index.ts	80.00%	0 Missing and 1 partial ⚠️

Additional details and impacted files

@@             Coverage Diff             @@
##             main    #2880       +/-   ##
===========================================
+ Coverage   32.57%   77.84%   +45.27%     
===========================================
  Files          14     1049     +1035     
  Lines         703    19470    +18767     
  Branches      119     3818     +3699     
===========================================
+ Hits          229    15157    +14928     
- Misses        474     2969     +2495     
- Partials        0     1344     +1344     

☔ 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.

[nick-Ag]

Is this something you think would be worth it to add a unit test for? One that fails if some future developer changes this for some reason

[varadarajan-tw]

@nick-Ag - Good idea. Added a snapshot test for batch key configuration.