RedfishPkg/RedfishPlatformConfigDxe: Fix string assert issue

When calling SetValue() with string type input, there is
assertion of providing zero string ID to HII string function.
Fix this issue by creating string ID for input string buffer.
Fix Unicode and Ascii code convert issue together.
Add text op-code support

Signed-off-by: Nickle Wang <nicklew@nvidia.com>
Cc: Abner Chang <abner.chang@amd.com>
Cc: Igor Kulchytskyy <igork@ami.com>
Reviewed-by: Abner Chang <abner.chang@amd.com>
Reviewed-by: Igor Kulchytskyy <igork@ami.com>

RedfishPkg/RedfishPlatformConfigDxe/RedfishPlatformConfigDxe.h

@@ -78,4 +78,18 @@ typedef struct {
 #define REDFISH_PLATFORM_CONFIG_DEBUG    DEBUG_VERBOSE
 #define REDFISH_MENU_PATH_SIZE           8
 
+/**
+  Convert input unicode string to ascii string. It's caller's
+  responsibility to free returned buffer using FreePool().
+
+  @param[in]  UnicodeString     Unicode string to be converted.
+
+  @retval CHAR8 *               Ascii string on return.
+
+**/
+CHAR8 *
+StrToAsciiStr (
+  IN  EFI_STRING  UnicodeString
+  );
+
 #endif