feat(build): clean snapshot artifacts on cleanApp hook

This fixes NativeScript/nativescript-cli#3335

Author: Mitko-Kerezov

Diff for: lib/before-cleanApp.js

@@ -0,0 +1,4 @@
+const ProjectSnapshotGenerator = require("../snapshot/android/project-snapshot-generator");
+module.exports = function (hookArgs) {
+	ProjectSnapshotGenerator.cleanSnapshotArtefacts(hookArgs.platformInfo.projectData.projectDir);
+}

Diff for: package.json

@@ -15,6 +15,11 @@
         "script": "lib/before-prepareJS.js",
         "inject": true
       },
+      {
+        "type": "before-cleanApp",
+        "script": "lib/before-cleanApp.js",
+        "inject": true
+      },
       {
         "type": "after-prepare",
         "script": "lib/after-prepare.js",