Rename catch_stream -> catch_reusable_string_stream

After everything else was split out, this name much reflects the
actual contents of the file(s).

src/catch2/internal/catch_debug_console.cpp

@@ -9,12 +9,13 @@
 #include <catch2/internal/catch_debug_console.hpp>
 
 #include <catch2/internal/catch_config_android_logwrite.hpp>
-#include <catch2/internal/catch_stream.hpp>
 #include <catch2/internal/catch_platform.hpp>
 #include <catch2/internal/catch_windows_h_proxy.hpp>
 #include <catch2/catch_user_config.hpp>
 #include <catch2/internal/catch_stdstreams.hpp>
 
+#include <ostream>
+
 #if defined(CATCH_CONFIG_ANDROID_LOGWRITE)
 #include <android/log.h>