Move touchpad kcm_init phase

Summary:
Touchpad's kcminit only sets some x atoms on an alrady running X.

There's an argument that we want this done before all the apps restore,
but we don't need to delay starting plasmashell for this.

Phase 1 happens between these two points.

For wayland libinput this does nothing anyway
For the new X libinput this does nothing anyway

Test Plan: Read code.

Reviewers: #plasma, hein

Reviewed By: #plasma, hein

Subscribers: plasma-devel

Tags: #plasma

Differential Revision: https://phabricator.kde.org/D9200