add frontend-{app,plugin}-api packages

Co-authored-by: Fredrik Adelöw <freben@gmail.com>
Co-authored-by: Johan Haals <johan.haals@gmail.com>
Co-authored-by: Vincenzo Scamporlino <vincenzos@spotify.com>
Co-authored-by: Philipp Hugenroth <philipph@spotify.com>
Co-authored-by: Camila Belo <camilaibs@gmail.com>
Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>

packages/frontend-plugin-api/package.json

@@ -0,0 +1,32 @@
+{
+  "name": "@backstage/frontend-plugin-api",
+  "version": "0.0.0",
+  "main": "src/index.ts",
+  "types": "src/index.ts",
+  "license": "Apache-2.0",
+  "private": true,
+  "publishConfig": {
+    "access": "public",
+    "main": "dist/index.esm.js",
+    "types": "dist/index.d.ts"
+  },
+  "backstage": {
+    "role": "web-library"
+  },
+  "scripts": {
+    "start": "backstage-cli package start",
+    "build": "backstage-cli package build",
+    "lint": "backstage-cli package lint",
+    "test": "backstage-cli package test",
+    "clean": "backstage-cli package clean",
+    "prepack": "backstage-cli package prepack",
+    "postpack": "backstage-cli package postpack"
+  },
+  "devDependencies": {
+    "@backstage/cli": "workspace:^",
+    "@testing-library/jest-dom": "^5.10.1"
+  },
+  "files": [
+    "dist"
+  ]
+}