Offer to store Account Number in password manager

[Rawa]

When users create new account prompt their password manager, if available, to store the password.

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This change is 

[linear]

DROID-1854 Offer to store the account with CredentialManager on WelcomeScreen

[Pururun]

I found three things while testing:

1. The account number is saved as a password and not a username. I assume this intentional?
2. When trying to log in to the app I do not get prompted to use my stored account number. I guess this is because the input field is not a password. IIRC we do not want it to be a password for reasons...
3. When trying to log in on the homepage I also do not get prompted. I guess this is becase the account is saved under mullvadvpn.mullvad.net is there a way to change this?

Reviewed 3 of 3 files at r1, 5 of 5 files at r2, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved

[Rawa]

1. Yes, this is intentional, since the account number in closer to a password than a username and a bit of a secret that you don't share. This also means that password managers won't show it w/o user explicitly revealing it like on our account page.
2. That would part of another feature, with Compose 1.8.0 we can offer autofill from keyboard, then if we want to offer to store on login that would be yet another feature.
3. Yes, there is nothing linking the password entry to the website at this moment, I'm a bit uncertain about the integration to make it work with the website (if it is supported at all). But there is something called digital asset links (https://developer.android.com/identity/sign-in/credential-manager#add-support-dal) that allows us to add a link to our webiste as well, if this would be forwarded to the website with the store password request I'm not sure of though.

Reviewable status: 8 of 10 files reviewed, all discussions resolved

[Pururun]

1. 👍
2. Right, let's wait until then again.
3. I think it is fine with this feature then, just maybe create a new issue if we want to explore that in the future.

Reviewable status: 3 of 10 files reviewed, all discussions resolved

[Pururun]

Reviewed 7 of 7 files at r4, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved

PR Overview

This PR adds a feature to prompt the password manager to store a new account number during account creation by updating dependencies and documentation.

• Added the androidx-credentials dependency in the Gradle versions file.
• Updated CHANGELOG.md to reflect the new functionality.

Reviewed Changes

File	Description
android/gradle/libs.versions.toml	Added the androidx-credentials dependency for password manager usage
android/CHANGELOG.md	Added changelog entry describing the new account number storage prompt

Copilot reviewed 10 out of 10 changed files in this pull request and generated no comments.

[Pururun]

Reviewed 2 of 2 files at r5, all commit messages.
Reviewable status: complete! all files reviewed, all discussions resolved