ACTION-91: CableLabs eme testing

Here are the details of the EME tests and related infrastructure that CableLabs is creating and will make available to the HTML WG.

The tests will verify these EME Wiki use cases:
Simple Streaming of a Specific Title<https://www.w3.org/wiki/HTML/Media_Task_Force/EME_Use_Cases#Simple_Streaming_of_a_Specific_Title>
Limited Concurrent Streams via Key Renewal<https://www.w3.org/wiki/HTML/Media_Task_Force/EME_Use_Cases#Limited_Concurrent_Streams_via_Key_Renewal>
Limited Concurrent Streams via Key Release<https://www.w3.org/wiki/HTML/Media_Task_Force/EME_Use_Cases#Limited_Concurrent_Streams_via_Key_Release>
Persisted License Offline<https://www.w3.org/wiki/HTML/Media_Task_Force/EME_Use_Cases#Persisted_License_.2F_Offline>
Delete Cached Licenses<https://w3c.github.io/encrypted-media/#widl-MediaKeySession-remove-Promise-void>
Player to Ignore Cached Licenses<https://w3c.github.io/encrypted-media/#idl-def-MediaKeySession>
License/ Key Rotation<https://www.w3.org/wiki/HTML/Media_Task_Force/EME_Use_Cases#License.2FKey_Rotation>

The tests will use the W3C test harness. The client player is DASH.js. Protected test content will be created for clear key, Adobe, Widevine and PlayReady CDMs.

Bob