Update every example to include mediation="required"

[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