feat(core): do not rebuild native if prebuilt is present

According to documentation, this checks for an existing prebuild for the
current arch and skip building in `packages/core/build` if it found it.

"The install script will check if a compatible prebuild is bundled.
If so it does nothing. If not it will run node-gyp rebuild to produce a build.
This means that if the user using your module has disabled install scripts your
module will still work (!) as long as a compatible prebuild is bundled."

https://github.com/prebuild/prebuildify

Author: GuillaumeLagrange

packages/core/package.json

@@ -2,6 +2,9 @@
   "name": "@codspeed/core",
   "version": "5.0.0-alpha.2",
   "description": "The core Node library used to integrate with Codspeed runners",
+  "scripts": {
+    "install": "node-gyp-build"
+  },
   "keywords": [
     "codspeed",
     "benchmark",