Preemptively add corresponding runtime dependency when adding a platform #5425
Description
Is your feature request related to a problem? Please describe.
In order to add a platform, the runtime dependency has to be added first, or else npm continues to run indefinitely.
Describe the solution you'd like
When running ns platform add {android,ios}, check package.json for the dependency and run npm i @nativescript/{android,ios} if it is absent.
Describe alternatives you've considered
Run those command manually.
Additional context