EME test status

All,

I have updated the test framework to support Microsoft PlayReady servers as
well as the DRMToday server and also to support configuration of server
certificates. The server to be used is configured in the
scripts/drm-messagehandler.js (by commenting servers in/out).

At present, the persistent-usage-record tests (in the PR listed below)
require one of the Microsoft servers to be used if you are testing
PlayReady. We have access to a test version of the DRMToday servers which
also support this, but I have not integrated that yet.

The keyStatuses test (in the PR listed below) requires the DRMToday server,
because that test relies on getting a license response containing two keys.
This happens based on configuration of the DRMToday, whereas for the
Microsoft servers we can only supply a single content key in the request.

As I say, we may in due course be able to support all tests with the
DRMToday server. If we end up needing different servers for different tests
I will add support for configuring server capabilities and test
requirements.

The following Pull Requests are open for review:
- Persistent Usage Record DRM tests
<https://github.com/w3c/web-platform-tests/pull/3478> - these pass on Edge
with the polyfill
- Persistent License Clear Key tests
<https://github.com/w3c/web-platform-tests/pull/3424> - these pass on all
browsers with (large) polyfill
- KeyStatuses test <https://github.com/w3c/web-platform-tests/pull/3490>
- Additional setMediaKeys tests
<https://github.com/w3c/web-platform-tests/pull/3494>

I am working on Persistent License DRM tests, which should be available
shortly.

Of the tests originally submitted by Google, the following remain to be
migrated:
- encrypted-media-clear-key-invalid-license.html
- encrypted-media-clearkey-update-non-ascii-input.html
- encrypted-media-keystatuses-multiple-updates.html
- encrypted-media-onencrypted.html
- encrypted-media-playback-encrypted-and-clear-sources.html
- encrypted-media-playback-multiple-sessions.html
- encrypted-media-requestmediakeysystemaccess.html
- encrypted-media-reset-src-after-setmediakeys.html
- encrypted-media-session-closed-event.html
- encrypted-media-setmediakeys-again-after-playback.html
- encrypted-media-setmediakeys-again-after-resetting-src.html
- encrypted-media-setmediakeys-at-same-time.html
- encrypted-media-setmediakeys-multiple-times-with-different-mediakeys.html
- encrypted-media-setmediakeys-multiple-times-with-the-same-mediakeys.html
- encrypted-media-setmediakeys-to-multiple-video-elements.html
- encrypted-media-syntax.html
- encrypted-media-unique-origin.html
- encrypted-media-update-disallowed-input.html
- encrypted-media-waiting-for-a-key.html

(There are some other tests in the Google directory, but there are
Chromium-specific).

...Mark