Use NamedEnum for printing Entry type

Currently, we are using InputMessage::typeToString, a manually written
function, to print the entry type.

Let's use "NamedEnum" instead to simplify the process of adding new
types.

Bug: 167947340
Test: compile only
Change-Id: I26d0a469bf93adbe2795d8a378c25e6ded891274
4 files changed