clampPosition function for dragging display blocks

Uses the algorithm in the prototype and the design doc
(go/extend-cd-settings).

Bug: b/352650922
Test: atest TopologyClampTest.kt
Flag: com.android.settings.flags.display_topology_pane_in_display_list
Change-Id: I8d8d4427f5d5dc069b1529f8ca6ac2cee259ee8e