Exposed function to set digital credentials presentment mechanism fro…

[asghol]

…m intent (#1468)

Fixes #1468

Extracted the logic that takes a credential request and turns it into a DigitalCredentialsPresentmentMechanism so that single activity apps and apps that want to create their own visuals can still reuse that part of Multipaz. Tried to make the API surface strict enough to not complicate the logic inside but also leave little room for confusion.

Some thoughts:

• Expecting consuming apps to turn the incoming intent into a ProviderGetCredentialRequest first since single activity apps will likely check whether the intent is consumable through retrieveProviderGetCredentialRequest(intent: Intent).

• Expecting consuming apps to pass in a function for setResult so that other results than RESULT_OK is possible. This might not be needed so hoping for some feedback on this part.

• Tests pass

• Changelog updated as it is a new public facing function

• Manually tested

• Commit message is as short as I could make it

Example:
In the screenshot below, I've used the introduced function to set the presentation mechanism from a view model that belongs to a single activity app. It is not a polished example but a working one showing that it allows this type of app to make use of this part of multipaz as well.

[asghol]

Found something that should be fixed:

• Exposed functions that can throw should be marked as such (setPresentmentModelMechanism)

[davidz25]

Sorry for the delay here. Definitely supportive of the request to make the code generally more reusable... but we're currently reworking / simplifying some of the models / code related to presentment. I'll circle back here once that has landed!

[asghol]

No worries, did this to get more understanding as well as hoping to make this easier to reuse. Not waiting for this to be merged so no rush at all 😄