QChar: add FormFeed (FF) special character

[ChangeLog][QtCore][QChar] Added FormFeed (FF) special character.

Fixes: QTBUG-77089
Change-Id: I1024ee42da0c4323953afffd15b245a508f545f0
Reviewed-by: Edward Welbourne <edward.welbourne@qt.io>

src/corelib/text/qchar.cpp

@@ -572,6 +572,7 @@ QT_BEGIN_NAMESPACE
     \value Null A QChar with this value isNull().
     \value Tabulation Character tabulation.
     \value LineFeed
+    \value FormFeed
     \value CarriageReturn
     \value Space
     \value Nbsp Non-breaking space.

src/corelib/text/qchar.h

@@ -78,6 +78,7 @@ public:
         Null = 0x0000,
         Tabulation = 0x0009,
         LineFeed = 0x000a,
+        FormFeed = 0x000c,
         CarriageReturn = 0x000d,
         Space = 0x0020,
         Nbsp = 0x00a0,

tests/manual/diaglib/textdump.cpp

@@ -44,6 +44,9 @@ static const EnumLookup specialCharactersEnumLookup[] =
 #if QT_VERSION >= 0x050000
     {QChar::Tabulation, "Tabulation"},
     {QChar::LineFeed, "LineFeed"},
+#  if QT_VERSION >= 0x050e00
+    {QChar::FormFeed, "FormFeed"},
+#  endif
     {QChar::CarriageReturn, "CarriageReturn"},
     {QChar::Space, "Space"},
 #endif