Require modules dynamically when generating snapshot

[sis0k0]

Issue Checklist

• You are submitting: a feature request
• You verified that this is a real problem by searching the [NativeScript Forum] and the other [issues] in this repo.
• You checked our [demo apps] and the [documentation] for sample usage.

Problem

Currently, the modules that are executed when generating snapshots are the ones that are required in the vendor.ts file. With webpack 4 all node packages that are used in the app will be moved to one separate chunk. That makes the vendor.ts only needed when generating snapshots.

Proposed solution

We can dynamically generate requires for the modules that should be executed and add them to the 'snapshotted' chunk. That way, we won't need a separate vendor.ts file.