input: fix -Wformat warnings

These occur when an enum value is formatted as an integer without a
cast. In all these cases the debug logs are nicer if we use the actual
name of the enum value, so wrap them all in ftl::enum_string calls.

Bug: 245989146
Test: Check there are no -Wformat warnings in the output of
      $ m checkinput
Change-Id: I26333123e9fb445f1640c5e73757ddf4ad2d6e98