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.

(cherry picked from commit 14c0da88a93aa7b1aa71d5e7e923b537f0d419f3)

Change-Id: I6195fc0a8ceedfc7fd1a92bdd0acc55ace2c1232
diff --git a/update_attempter.h b/update_attempter.h
index 40c7382..92683e6 100644
--- a/update_attempter.h
+++ b/update_attempter.h
@@ -31,9 +31,9 @@
 
 #include "debugd/dbus-proxies.h"
 #include "update_engine/chrome_browser_proxy_resolver.h"
+#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/libcros_proxy.h"
 #include "update_engine/omaha_request_params.h"