Move PropertyMap from libutils to libinput

The input code is the only customer of PropertyMap. For easier
maintenance and eventual removal of it, move it to libinput.

Currently, the caller is responsible for managing the lifecycle of the
returned outMap when calling PropertyMap::load. However, the fact that
the function call allocates new memory is not obvious from the function
signature.

In a separate commit, I will refactor the function to return
Result<unique_ptr<>> to make it less errorprone.
In this commit, only move the files around to make code reviews easier.

Bug: 163171599
Test: atest inputflinger_tests
Change-Id: I316084886c3f09a1776fdb449d2f03d0563b66c1