Put keyboard button in navigation bar when possible

Summary:
In the remote input activity, the keyboard button was in the overflow menu, even though it fit on the navigation bar. The previous code used the wrong namespace, so this fixes it.

BUG: 390640

Before:
{F5729325}

After:
{F5729326}

Reviewers: #kde_connect, nicolasfella

Reviewed By: #kde_connect, nicolasfella

Subscribers: nicolasfella

Differential Revision: https://phabricator.kde.org/D10827