chore: Extract ItemStore to own package

Signed-off-by: Sebastian Malton <sebastian@malton.name>

open-lens/package.json

@@ -189,6 +189,7 @@
     "@k8slens/ensure-binaries": "^6.5.0",
     "@k8slens/error-boundary": "^1.0.0",
     "@k8slens/event-emitter": "^1.0.0",
+    "@k8slens/item-store": "^1.0.0",
     "@k8slens/feature-core": "^6.5.0",
     "@k8slens/json-api": "^1.0.0-alpha.3",
     "@k8slens/keyboard-shortcuts": "^1.0.0",