Allow bypassing private DNS via setNetworkForProcess.

Currently, bypassing private DNS requires calling
setNetworkForResolv, which is not accessible except through
the deprecated setProcessDefaultNetworkForHostResolution API.
Allow apps to do this via setNetworkForProcess as well.

Bug: 112869080
Test: atest netd_unit_test netd_integration_test resolv_unit_test resolv_integration_test
Change-Id: I033d1ba3f0227cb54eec352d4b2ded8b3ffa8539