Publish viewUid and trackUid with wheel events

[keller-mark]

Description

What was changed in this pull request?

This pull request adds the properties trackUid and viewUid to the object that is published on wheel events (that have been registered via .on('wheel', callback) using the JS API).

Why is it necessary?

Currently, wheel events only publish the track with which they are associated. However, this could be ambiguous if one wants to identify the track since there is no information about the parent view. To be more precise about which track a wheel event is associated with, we can also include the view UID in the event object.

Fixes #___

Checklist

• Set proper GitHub labels (e.g. v1.6+, ignore if you don't know)
• Unit tests added or updated
• Documentation added or updated
• Example(s) added or updated
• Update schema.json if there are changes to the viewconf JSON structure format
• Screenshot for visual changes (e.g. new tracks or UI changes)
• Updated CHANGELOG.md