fix loginactivity intent to use accountmanager instead of davx5

Description

fixes e/backlog#6523 (closed) - users are misdirected, being prompted to install the play-version of davx5 when a fork is already installed in the /e/ default install.

It has still some dysfunction, but much less so. The nextcloud-sso provider wouldn't work as far as I can see. But if a user hasn't setup an account yet it will make calendars available after having gone through the login activity.

Tests

• Q&A should go through Calendars -> add CalDAV Calendar and complete the login flow

Issues

• e/backlog#6523 (closed)

Summary by CodeRabbit

• Bug Fixes
  • Updated the DavX5 login functionality to reflect a change in the package name, ensuring proper activity resolution for login.

This change aims to maintain seamless login experiences by adapting to the modified dependencies while ensuring the existing checks remain intact.