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.h b/update_attempter.h
index af56f55..104975c 100644
--- a/update_attempter.h
+++ b/update_attempter.h
@@ -32,9 +32,9 @@
 #if USE_LIBCROS
 #include "update_engine/chrome_browser_proxy_resolver.h"
 #endif  // USE_LIBCROS
+#include "update_engine/certificate_checker.h"
 #include "update_engine/client_library/include/update_engine/update_status.h"
 #include "update_engine/common/action_processor.h"
-#include "update_engine/common/certificate_checker.h"
 #include "update_engine/common/cpu_limiter.h"
 #include "update_engine/omaha_request_params.h"
 #include "update_engine/omaha_response_handler_action.h"