Removes the mandatory mediation requirement for digital credentials API

[mohamedamir]

Updates the Digital Credentials API implementation to remove the strict requirement for mediation: 'required'. This change allows navigator.credentials.create() and navigator.credentials.get() to be called without specifying a mediation hint.

This aligns with recent specification changes and improves developer experience.

[mohamedamir]

@marcoscaceres We should ideally add tests that requests succeed for different mediation values.
But that's not possible before having proper testing automation support. Do you have other ideas? How can we best track this work?

Maybe I add the tests as part of this PR and we modify them later once we have the webdriver changes are available?

WDYT?

[mohamedamir]

@marcoscaceres We should ideally add tests that requests succeed for different mediation values. But that's not possible before having proper testing automation support. Do you have other ideas? How can we best track this work?

Maybe I add the tests as part of this PR and we modify them later once we have the webdriver changes are available?

WDYT?

As per our discussion, we should use the AbortController to abort request and test that no other error is thrown.

[mohamedamir]

@marcoscaceres We should ideally add tests that requests succeed for different mediation values. But that's not possible before having proper testing automation support. Do you have other ideas? How can we best track this work?
Maybe I add the tests as part of this PR and we modify them later once we have the webdriver changes are available?
WDYT?

As per our discussion, we should use the AbortController to abort request and test that no other error is thrown.

@marcoscaceres I have updated the tests as per our discussion!
Could you please take a look?

Thank you!