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/common/http_fetcher_unittest.cc b/common/http_fetcher_unittest.cc
index 6f3e480..0f34475 100644
--- a/common/http_fetcher_unittest.cc
+++ b/common/http_fetcher_unittest.cc
@@ -44,11 +44,11 @@
 #include "update_engine/common/fake_hardware.h"
 #include "update_engine/common/file_fetcher.h"
 #include "update_engine/common/http_common.h"
-#include "update_engine/common/libcurl_http_fetcher.h"
 #include "update_engine/common/mock_http_fetcher.h"
 #include "update_engine/common/multi_range_http_fetcher.h"
 #include "update_engine/common/test_utils.h"
 #include "update_engine/common/utils.h"
+#include "update_engine/libcurl_http_fetcher.h"
 #include "update_engine/mock_proxy_resolver.h"
 #include "update_engine/proxy_resolver.h"