Allows settings applications on other platforms to re-use values by
migrating to Settings.secure and moving HideNonSystemOverlayMixin to
SettingsLib.
Bug: 184967544
Test: atest SettingsUnitTests
Change-Id: If9aaeca29ebb8b481d75622934503e368d7435d3
If opening app has requested only a subset of fields
Test: manual - launch from an app, filtered and unfiltered, for
normal channels and conversations
Bug: 177246841
Change-Id: Ifd70478101d1ea1340d2ecc55033fab55e65ca92
Change-Id: I5194b959c82b2cfa7990c84285aaf69464cff3a8