Update XDM with latest Media Analytics changes

## What are the schemas that are affected by the issue
- `media-timed-asset-reference.schema.json`
- `media-timed-asset-view-details.schema.json`
- `media-timed-qoe.schema.json`
- `media-timed.schema.json`
- `unique-time-played.schema.json` [NEW]

## What are examples of products that are impacted by the issue
- Adobe Media Analytics

Internal JIRA issue: https://jira.corp.adobe.com/browse/VA-2129

High-level changes:
- most of the PR relates to the addition of audio streams and the new properties they come with (e.g. `xmpDM:artist`);
- support for downloaded content; note that **downloaded does not mean offline**, as downloaded content can be played while the device is online;
- support for the new `uniqueTimePlayed` metrics;
- support for error code lists in the QoE schema;

Start by reviewing media-timed-asset-reference.schema.json, media-timed-asset-view-details.schema.json, media-timed-qoe.schema.json, media-timed.schema.json, and the new unique-time-played.schema.json. Use the listed Adobe Media Analytics changes and VA-2129 as the requirements; done means the schemas support audio streams, downloaded content, uniqueTimePlayed metrics, and QoE error code lists.

Written by the indexing model from the issue text.