Setup interfaces for IPv6 tethering

Including:
    - set the interface for router mode (accept_ra = 0)
    - reset the interface for client mode (accept_ra = 1)
    - InterfaceController::setAcceptIPv6Ra()
    - InterfaceController::setAcceptIPv6Dad()
    - make InterfaceController static
    - refactor for more modern C++ usage here and there
    - sporadic style guide fixes

Bug: 9580643
Change-Id: Ia557c8770e18c58b12ad16d982c63b6ebd525516
diff --git a/server/Controllers.cpp b/server/Controllers.cpp
index 07e5653..85c7c96 100644
--- a/server/Controllers.cpp
+++ b/server/Controllers.cpp
@@ -19,7 +19,9 @@
 namespace android {
 namespace net {
 
-Controllers::Controllers() : clatdCtrl(&netCtrl) {}
+Controllers::Controllers() : clatdCtrl(&netCtrl) {
+    InterfaceController::initializeAll();
+}
 
 Controllers* gCtls = nullptr;