Clean up output stream

Author: Trenly

src/AppInstallerCLICore/ChannelStreams.h

@@ -94,10 +94,6 @@ namespace AppInstaller::CLI::Execution
         OutputStream& operator<<(const VirtualTerminal::ConstructedSequence& sequence);
         OutputStream& operator<<(const std::filesystem::path& path);
 
-        inline bool IsEnabled() {
-            return m_enabled;
-        }
-
     private:
         // Applies the format for the stream.
         void ApplyFormat();