add: abstract search functionality to core + adjust meilisearch-plugin

add SearchService interface to medusa-interfaces
add DefaultSearchService skeleton implementation to core
add search-index.js loader to core for indexing db documents
add SearchSubscriber to core
add loadToSearchEngine method in ProductService
switch order of loaders in core to load subscriptions AFTER plugins
adjust service and loader for medusa-plugin-meilisearch

packages/medusa-plugin-meilisearch/package.json

@@ -24,7 +24,7 @@
     "body-parser": "^1.19.0",
     "lodash": "^4.17.21",
     "medusa-core-utils": "^1.1.20",
-    "medusa-interfaces": "^1.1.21",
+    "medusa-interfaces": "^1.1.23",
     "meilisearch": "^0.20.0"
   },
   "devDependencies": {