feat: ads error interface

[wseymour15]

The implementation for an error interface specifically for ads. An error can be set on the player.ads.error() function by passing it an object containing a type string and a metadata object containing any custom data that is desired. The bulk of the work is in ads.js

There are examples of usage in this repo, but this can also be used when contrib ads is pulled into a user's repo. Errors can be handled or set by the user.

Proposed Changes:

• Error interface so we can listen for ad errors in other ares of the player.
• Trigger a handful of errors
• Test Changes
• Documentation Changes