🔑 Support for client certificates

[Waler]

In order to secure the connection to Nextcloud on TLS level, it would be good if the app could support client certificates. If the client certificate is not sent on handshake, the server prevents access to Nextcloud logon page. This would provide a second line of defense.

Expected behaviour
Memories app should support client certificates as other apps like nextcloud android app does since version 3.29.0. (nextcloud/android#603)

[Elv1zz]

I just wanted to open the same feature request 👍

Just checked: The memories Android app sadly does not use the nextcloud android-library but seems to implement all communication on its own. Otherwise it would have been rather easy to just make use of the TLS client certificate handling added to that library.

Since I integrated the certificate handling into the nextcloud library (PRs 1048 and 1308) and app (PRs 11314 and 12408) I'd be willing to also integrate it here -- especially as I'd like to use the awesome memories app in a secure manner as well. But I might need some guidance in where to best interact with the login procedure and overall nextcloud communication. And, of course, before I start, I would like to have some indication that this kind of feature would be integrated into the app.

[pulsejet]

PRs are welcome always, I've just had no time to get anything done here recently. Switching to the android library sounds like the right thing to do. Right now, we just use the login flow v2, I don't think there's anything special here. The only thing that might be different is the token needs to be injected to the webview headers and make sure that native functions like video streaming and file downloads use the right token and TLS settings.

[Elv1zz]

I just opened draft PR #1216 for this. Anybody willing to review and test it is welcome