Remove libcurl support from update_engine_sideload.

While sideloading an update from recovery we don't need nor want to
download payload from HTTP(S) URLs, only local file:// are supported.
This patch moves libcurl_http_fetcher and certificate_checker files out
of libpayload_consumer dropping the libcurl and libssl dependencies from
it and the update_engine_sideload.

Bug: 27178350
TEST=build UE for Brillo and Android. Unittests still pass and
update_engine_sideload doesn't link to libcurl.

Change-Id: Iffefdb094654f7277dc825c041fe55aac9ee8756
diff --git a/update_attempter.cc b/update_attempter.cc
index 5e63ef6..8afc395 100644
--- a/update_attempter.cc
+++ b/update_attempter.cc
@@ -39,17 +39,17 @@
 #include <policy/libpolicy.h>
 #include <update_engine/dbus-constants.h>
 
+#include "update_engine/certificate_checker.h"
 #include "update_engine/common/boot_control_interface.h"
-#include "update_engine/common/certificate_checker.h"
 #include "update_engine/common/clock_interface.h"
 #include "update_engine/common/constants.h"
 #include "update_engine/common/hardware_interface.h"
-#include "update_engine/common/libcurl_http_fetcher.h"
 #include "update_engine/common/multi_range_http_fetcher.h"
 #include "update_engine/common/platform_constants.h"
 #include "update_engine/common/prefs_interface.h"
 #include "update_engine/common/subprocess.h"
 #include "update_engine/common/utils.h"
+#include "update_engine/libcurl_http_fetcher.h"
 #include "update_engine/metrics.h"
 #include "update_engine/omaha_request_action.h"
 #include "update_engine/omaha_request_params.h"