[CMD] Fix missing/misplaced newlines at end of displayed errors and prompts.

ConInString() should display a newline when it encounters the terminating
carriage-return pressed by the user for ending string output.
+ Remove the extra \n hacks in FilePromptYN[A].

Improve outputted strings from DATE and TIME commands.
+ Rename some STRING_***_ERROR defines.

CORE-18489

base/shell/cmd/console.h

@@ -14,7 +14,6 @@ extern CON_PAGER  StdOutPager;
 // extern BOOL   bIgnoreEcho;
 // extern BOOL   bExit;
 
-VOID ConInDummy (VOID);
 VOID ConInDisable (VOID);
 VOID ConInEnable (VOID);
 VOID ConInFlush (VOID);