[PM-20247] Initialize user-core library (#15029)

* Initialize user-core library

* Run `npm install`

* Fix patched generator bug

libs/user-core/project.json

@@ -0,0 +1,27 @@
+{
+  "name": "user-core",
+  "$schema": "../../node_modules/nx/schemas/project-schema.json",
+  "sourceRoot": "libs/user-core/src",
+  "projectType": "library",
+  "tags": [],
+  "targets": {
+    "build": {
+      "executor": "@nx/js:tsc",
+      "outputs": ["{options.outputPath}"],
+      "options": {
+        "outputPath": "dist/libs/user-core",
+        "main": "libs/user-core/src/index.ts",
+        "tsConfig": "libs/user-core/tsconfig.lib.json",
+        "assets": ["libs/user-core/*.md"]
+      }
+    },
+    "test": {
+      "executor": "@nx/jest:jest",
+      "outputs": ["{workspaceRoot}/coverage/{projectRoot}"],
+      "options": {
+        "jestConfig": "libs/user-core/jest.config.js",
+        "passWithNoTests": true
+      }
+    }
+  }
+}