Create launcher icon pack overlay

Bug: 126738409
Test: builds

$ adb shell cmd overlay enable-exclusive --user 0 com.android.theme.icon_pack.rounded.launcher
$ adb shell cmd overlay enable-exclusive --user 0 com.android.theme.icon_pack.filled.launcher
$ adb shell cmd overlay enable-exclusive --user 0 com.android.theme.icon_pack.circular.launcher

Change-Id: Ic15b6fbf8e4c2d643357e29ec65782daeaaceb52