fix(core): Fix issues with community node installation (no-changelog) (#5481)

This fixes the following issues:
* After a community node is installed, we were not calling `postProcessLoaders`, which was causing a bunch of unexpected behaviors, and sometimes even crashes. This was only happening in the session where the package was installed. After a crash, the restarted service was working without these issues.
* After a community node is installed, the icon for the nodes and credentials were missing in the UI, as we were creating one icons route per installed package at startup, and this did not handle newly installed packages. restarting the service fixes this issue as well.

Fixes https://community.n8n.io/t/showing-weird-count-on-community-nodes/23035

packages/core/src/DirectoryLoader.ts

@@ -45,7 +45,7 @@ export abstract class DirectoryLoader {
 	types: Types = { nodes: [], credentials: [] };
 
 	constructor(
-		protected readonly directory: string,
+		readonly directory: string,
 		protected readonly excludeNodes: string[] = [],
 		protected readonly includeNodes: string[] = [],
 	) {}