Remove direct dependency on libcutils

libcutils is Android-specific and does not exist in Linux/Chrome OS.
This patch removes direct dependency on it and instead creates an
abstract layer called os_utils which contain separate implementations
for Android (using libcutils) and other OSes.

Bug: 176847216
Tag: #refactor
Test: atest --host bluetooth_test_common

Change-Id: Ifaebbd2baf5d3f7d638d70b3a9b97a1cb7724d10