feat: shard modules and API integration tests (#6775)

what:

- runs module and api integration tests in matrix strategy
  - v28 of jest comes with sharding support, which we can utilize when we upgrade
- splits the tests by number of matrix jobs and run them in parallel
  - This introduced some flakiness in some specs, but couldn't reproduce locally. Those have been skipped for now.
- uses swc/jest for added performance
  - Locally, a chunk took 90 seconds with babel and 30 seconds with swc. 
  - This translated to 2 mins saved per shard in CI, but haven't tested this enough.

package.json

@@ -72,9 +72,9 @@
     "jest": "jest",
     "test": "turbo run test --concurrency=50% --no-daemon",
     "test:integration:packages": "turbo run test:integration --concurrency=50% --no-daemon --filter='./packages/*'",
-    "test:integration:api": "turbo run test:integration --concurrency=50% --no-daemon --filter=integration-tests-api",
+    "test:integration:api": "turbo run test:integration:chunk --concurrency=50% --no-daemon --filter=integration-tests-api",
     "test:integration:plugins": "turbo run test:integration --concurrency=50% --no-daemon --filter=integration-tests-plugins",
-    "test:integration:modules": "turbo run test:integration --concurrency=50% --no-daemon --filter=integration-tests-modules",
+    "test:integration:modules": "turbo run test:integration:chunk --concurrency=50% --no-daemon --filter=integration-tests-modules",
     "test:integration:repositories": "turbo run test:integration --concurrency=50% --no-daemon --filter=integration-tests-repositories",
     "openapi:generate": "yarn ./packages/oas/oas-github-ci run ci --with-full-file",
     "medusa-oas": "yarn ./packages/oas/medusa-oas-cli run medusa-oas",