Fixed Header in 3 plugin pages: Run Command, Multimedia control, Remote input

Summary: Fixed Header in 3 plugins: Run Command, Multimedia control, Remote input

Test Plan:
build the Android APK and analyze the Header in Run Command,
Remote input and Multimedia control plugins.

Reviewers: KDE Connect, sredman

Reviewed By: KDE Connect, sredman

Subscribers: ltoscano, nicolasfella, albertvaka, sredman, kdeconnect

Tags: KDE Connect

Differential Revision: https://phabricator.kde.org/D17250