Move IdentityClient to backend-common

Signed-off-by: Nataliya Issayeva <nissayeva@users.noreply.github.com>

packages/backend-common/package.json

@@ -34,6 +34,7 @@
     "@backstage/config-loader": "^0.8.0",
     "@backstage/errors": "^0.1.4",
     "@backstage/integration": "^0.6.9",
+    "@backstage/plugin-auth-backend": "^0.4.5",
     "@backstage/types": "^0.1.1",
     "@google-cloud/storage": "^5.8.0",
     "@lerna/project": "^4.0.0",
@@ -54,6 +55,7 @@
     "git-url-parse": "^11.6.0",
     "helmet": "^4.0.0",
     "isomorphic-git": "^1.8.0",
+    "jose": "^1.27.1",
     "keyv": "^4.0.3",
     "keyv-memcache": "^1.2.5",
     "knex": "^0.95.1",