Adding logging to magnetic state changes.

This will help us debug the state of a magnetic interaction in relation
to external animation and input events from other notification
components. The logger uses the @NotificationLog buffer to avoid extra
clutter on the @NotificationRenderLog buffer.

Test: Presubmit and manual check of logs when swiping magnetic
  notifications
Flag: EXEMPT added logging information only.
Bug: 415279408
Change-Id: Ifcc78279b2e43985eafd7cb2a5d4a3ce240df0a9