Mark as many 3rd party JS library as possible as internal

Problem/Motivation

We're trying to reduce the number of libraries core uses, and reduce the API surface we're providing for contrib/projects. A few libraries can be marked as internal as we don't expect contrib to use or extend them.

Steps to reproduce

Proposed resolution

Generalize what we did with backbone in #3258931: Deprecate backbone and tag it internal:

1. deprecate core/<library>
2. create a new core/internal.<library> definition
3. replace all uses core/<library> with core/internal.<library>
4. update the vendor-update script

Remaining tasks

User interface changes

API changes

Data model changes

Release notes snippet