Use the network security config's cleartext settings

Previously DownloadManager only respected the manifest attribute, this
change makes DownloadManager handle both the manifest and the network
security config

Change-Id: I5666a1eea6278acc3864620a0e5a4c3ae37635b8
Fixes: 78028215
Test: atest CtsNetSecConfigDownloadManagerTestCases
4 files changed