[Security Solution] Auto-bundle Lists API OpenAPI specs (elastic#188407)

**Addresses**: elastic#184428

## Summary

This PR adds scripts for automatic bundling of Lists API OpenAPI specs as a part of PR pipeline. Corresponding resulting bundles are automatically committed in the Lists common package `kbn-securitysolution-lists-common` in the `docs/openapi/ess/` and `docs/openapi/serverless` folders (similar to elastic#186384).

.buildkite/scripts/steps/openapi_bundling/security_solution_openapi_bundling.sh

@@ -8,3 +8,6 @@ echo --- Security Solution OpenAPI Bundling
 
 (cd x-pack/plugins/security_solution && yarn openapi:bundle)
 check_for_changed_files "yarn openapi:bundle" true
+
+(cd packages/kbn-securitysolution-lists-common && yarn openapi:bundle)
+check_for_changed_files "yarn openapi:bundle" true

packages/kbn-securitysolution-lists-common/api/export_list_item/export_list_item.schema.yaml

@@ -5,6 +5,7 @@ info:
 paths:
   /api/lists/items/_export:
     post:
+      x-labels: [serverless, ess]
       operationId: ExportListItems
       x-codegen-enabled: true
       summary: Exports list items

packages/kbn-securitysolution-lists-common/api/find_list_item/find_list_item.schema.yaml

@@ -3,7 +3,7 @@ info:
   title: Find list items API endpoint
   version: '2023-10-31'
 paths:
-  /api/lists/_find:
+  /api/lists/items/_find:
     get:
       x-labels: [serverless, ess]
       operationId: FindListItems

packages/kbn-securitysolution-lists-common/api/import_list_item/import_list_item.schema.yaml

@@ -5,6 +5,7 @@ info:
 paths:
   /api/lists/items/_import:
     post:
+      x-labels: [serverless, ess]
       operationId: ImportListItems
       x-codegen-enabled: true
       summary: Imports list items