Accept lowercase SCRIPT subcommands (#987)

* Accept lower case script load

* More standard behaviour for slow parse command with missing/wrong arguments.

* dotnet format

* Match COMMAND UNKNOWN error message and expected test result.

---------

Co-authored-by: prvyk <github@privatemail.fastmailbox.net>
Co-authored-by: Badrish Chandramouli <badrishc@microsoft.com>

libs/server/Resp/CmdStrings.cs

@@ -56,6 +56,7 @@ static partial class CmdStrings
         public static ReadOnlySpan<byte> HELP => "HELP"u8;
         public static ReadOnlySpan<byte> help => "help"u8;
         public static ReadOnlySpan<byte> PING => "PING"u8;
+        public static ReadOnlySpan<byte> SCRIPT => "SCRIPT"u8;
         public static ReadOnlySpan<byte> HELLO => "HELLO"u8;
         public static ReadOnlySpan<byte> TIME => "TIME"u8;
         public static ReadOnlySpan<byte> RESET => "RESET"u8;
@@ -257,6 +258,7 @@ static partial class CmdStrings
         public const string GenericErrUnknownOptionConfigSet = "ERR Unknown option or number of arguments for CONFIG SET - '{0}'";
         public const string GenericErrUnknownOption = "ERR Unknown option or number of arguments for '{0}' command";
         public const string GenericErrUnknownSubCommand = "ERR unknown subcommand '{0}'. Try {1} HELP";
+        public const string GenericErrUnknownSubCommandNoHelp = "ERR unknown subcommand '{0}'.";
         public const string GenericErrWrongNumArgsTxn =
             "ERR Invalid number of parameters to stored proc {0}, expected {1}, actual {2}";
         public const string GenericSyntaxErrorOption = "ERR Syntax error in {0} option '{1}'";
@@ -317,6 +319,8 @@ static partial class CmdStrings
         // subcommand parsing strings
         public static ReadOnlySpan<byte> CAT => "CAT"u8;
         public static ReadOnlySpan<byte> DELUSER => "DELUSER"u8;
+        public static ReadOnlySpan<byte> EXISTS => "EXISTS"u8;
+        public static ReadOnlySpan<byte> FLUSH => "FLUSH"u8;
         public static ReadOnlySpan<byte> LOAD => "LOAD"u8;
         public static ReadOnlySpan<byte> LOADCS => "LOADCS"u8;
         public static ReadOnlySpan<byte> SETUSER => "SETUSER"u8;