[flexiglass] Renames KeyguardLongPress<*>

Now that these classes don't deal only with long-press (they also deal
with click and double click), "touch handling" is a more fitting name.

Fix: 344879669
Test: not tested, rename only
Flag: com.android.systemui.scene_container
Change-Id: I2063f040b057e2b15c4019b6c5390f0dd8a26a01