feat(stackoverflow): migrate to new frontend system

Signed-off-by: Camila Belo <camilaibs@gmail.com>

plugins/stack-overflow/package.json

@@ -5,9 +5,22 @@
   "types": "src/index.ts",
   "license": "Apache-2.0",
   "publishConfig": {
-    "access": "public",
-    "main": "dist/index.esm.js",
-    "types": "dist/index.d.ts"
+    "access": "public"
+  },
+  "exports": {
+    ".": "./src/index.ts",
+    "./alpha": "./src/alpha.tsx",
+    "./package.json": "./package.json"
+  },
+  "typesVersions": {
+    "*": {
+      "alpha": [
+        "src/alpha.tsx"
+      ],
+      "package.json": [
+        "package.json"
+      ]
+    }
   },
   "backstage": {
     "role": "frontend-plugin"
@@ -32,6 +45,7 @@
     "@backstage/config": "workspace:^",
     "@backstage/core-components": "workspace:^",
     "@backstage/core-plugin-api": "workspace:^",
+    "@backstage/frontend-plugin-api": "workspace:^",
     "@backstage/plugin-home-react": "workspace:^",
     "@backstage/plugin-search-common": "workspace:^",
     "@backstage/plugin-search-react": "workspace:^",