Don't require CM "mediation" to be specified explicitly (always 'required' for DC).

[samuelgoto]

Given #175, we are going to need to update every example and deployment to use mediation="required".

A few examples are, since this is backwards incompatible change:

1. https://openid.github.io/OpenID4VP/openid-4-verifiable-presentations-wg-draft.html#name-request
2. https://digitalcredentials.dev/
3. https://developer.chrome.com/blog/digital-credentials-api-origin-trial

And every demo app that was built against our API.

[timcappalli]

digitalcredentials.dev is updated (digitalcredentialsdev/digitalcredentials.dev@35b915b)

[marcoscaceres]

Blocked on w3c/webappsec-credential-management#256

@timcappalli, we should add "Update digitalcredentials.dev" to the PR Template, so we always remember to do that.

[timcappalli]

@marcoscaceres fyi: 60a44bf

[timcappalli]

@samuelgoto can this be closed?

[RByers]

Discussed in the call today. Our implementation today doesn't require developers to specify a mediation, which is how we want to keep it. So updating the title to reflect that we need to be sure this is covered by the specs and tests. It sounds like this is mostly w3c/webappsec-credential-management#256, though I assume we might also need some text in our spec too once that's resolved, right?