build: install mock-server when in dev environment

Author: LexLuengas

package-lock.json

@@ -38,7 +38,9 @@
     "test:docker": "bash ./test/docker/run-docker-test.bash",
     "test:deps": "npx depcheck --ignores=\"@types/*\"",
     "posttest": "npm run check",
-    "package": "npx yarn pack --filename openapi-cop.tgz"
+    "package": "npx yarn pack --filename openapi-cop.tgz",
+    "preinstall": "per-env",
+    "preinstall:development": "cd mock-server && npm install"
   },
   "dependencies": {
     "@types/express": "4.17.4",
@@ -56,6 +58,7 @@
     "lodash": "4.17.21",
     "openapi-backend": "3.9.2",
     "openapi-types": "10.0.0",
+    "per-env": "^1.0.2",
     "qs": "6.10.3",
     "request-promise-native": "1.0.9",
     "swagger-client": "3.18.4",