Port all available calls to libupdate_engine_client

This is as far as the port can go without improving the library itself.

Change-Id: I5d5dbf14b62746786364b2a7e1a9131d8ef7bfb1
Test: All affected commands still signal the daemon on dragonboard
Bug: 26233663
diff --git a/client_library/client_impl.cc b/client_library/client_impl.cc
index 3dba873..af9cb05 100644
--- a/client_library/client_impl.cc
+++ b/client_library/client_impl.cc
@@ -70,10 +70,11 @@
   return proxy_->ResetStatus(nullptr);
 }
 
-bool UpdateEngineClientImpl::SetTargetChannel(const string& in_target_channel) {
+bool UpdateEngineClientImpl::SetTargetChannel(const string& in_target_channel,
+                                              bool allow_powerwash) {
   return proxy_->SetChannel(
       in_target_channel,
-      true,
+      allow_powerwash,
       nullptr);
 }