[FX-1729] tracking for collections

[pepopowitz]

A collaboration with @anandaroop.

Addresses https://artsyproduct.atlassian.net/browse/FX-1729 (whose ticket number represents the smallest number expressible as the sum of two cubes in two different ways).

This PR is all about tracking within collections. The events that are to be tracked:

• [x] A "screenview" when you view a collection (completed previously)
• [x] A "tap" when you tap "Read more" in the collection description (completed previously, but the constants are updated in this PR)
• [x] ~A "success" event when you follow an artist~ (addressed by existing component)
• [x] ~A "success" event when you unfollow an artist~ (addressed by existing component)
• [x] A "tap" when you tap on "View more" in the featured artists list

[artsyit]

:rocket: PR was released in v1.21.24 :rocket: