build: add validate:ts script for TypeScript checking

Signed-off-by: pierre santamaria <[email protected]>

Author: Pivouane

package.json

@@ -10,6 +10,7 @@
     "build": "ng run netzgrafik-frontend:ngsscbuild",
     "build:standalone": "ng build --configuration=standalone",
     "build:standalonedemo": "ng build --configuration=standalonedemo",
+    "validate:ts": "tsc --noEmit --skipLibCheck",
     "test": "ng test -c ci",
     "format": "prettier --write .",
     "format:check": "prettier --check .",