use find_package(c-ares) instead of FindCares.cmake

Summary:
clearly made a mistake here, lack of cmake experience (thanks mingtaoy):

c-ares ships a CMake package (c-ares-config.cmake) that we should use instead of our bespoke FindCares.cmake

Reviewed By: afrind

Differential Revision: D81248145

fbshipit-source-id: 15b5595bac25f08dcf5faa7c3fb2efb10da3fc7b

Author: hanidamlaj

build/fbcode_builder/CMake/FindCares.cmake

@@ -0,0 +1,30 @@
+# Copyright (c) Meta Platforms, Inc. and affiliates.
+# All rights reserved.
+#
+# This source code is licensed under the BSD-style license found in the
+# LICENSE file in the root directory of this source tree.
+
+find_path(CARES_INCLUDE_DIR NAMES ares.h)
+find_library(CARES_LIBRARIES NAMES cares)
+
+include(FindPackageHandleStandardArgs)
+find_package_handle_standard_args(Cares DEFAULT_MSG CARES_LIBRARIES CARES_INCLUDE_DIR)
+
+mark_as_advanced(
+  CARES_LIBRARIES
+  CARES_INCLUDE_DIR
+)
+
+if(NOT TARGET cares)
+    if("${CARES_LIBRARIES}" MATCHES ".*.a$")
+    add_library(cares STATIC IMPORTED)
+    else()
+    add_library(cares SHARED IMPORTED)
+    endif()
+    set_target_properties(
+        cares
+        PROPERTIES
+            IMPORTED_LOCATION ${CARES_LIBRARIES}
+            INTERFACE_INCLUDE_DIRECTORIES ${CARES_INCLUDE_DIR}
+    )
+endif()