Utils: More forward declarations / drop unused headers [T-Z]

Round 1 - focus on headers.
For classes with initial in range [T-Z].

Replace QT_FORWARD_DECLARE_CLASS with QT_BEGIN_NAMESPACE and
QT_END_NAMESPACE and forward declare inside.

Change-Id: I4ac3a8391e6167aa2db3973a9f94a45ac3c8ebd1
Reviewed-by: hjk <hjk@qt.io>

src/libs/utils/textutils.cpp

@@ -165,7 +165,7 @@ int utf8NthLineOffset(const QTextDocument *textDocument, const QByteArray &buffe
 
 LineColumn utf16LineColumn(const QByteArray &utf8Buffer, int utf8Offset)
 {
-    Utils::LineColumn lineColumn;
+    LineColumn lineColumn;
     lineColumn.line = static_cast<int>(
                           std::count(utf8Buffer.begin(), utf8Buffer.begin() + utf8Offset, '\n'))
                       + 1;
@@ -221,7 +221,7 @@ void applyReplacements(QTextDocument *doc, const Replacements &replacements)
     int fullOffsetShift = 0;
     QTextCursor editCursor(doc);
     editCursor.beginEditBlock();
-    for (const Utils::Text::Replacement &replacement : replacements) {
+    for (const Text::Replacement &replacement : replacements) {
         editCursor.setPosition(replacement.offset + fullOffsetShift);
         editCursor.movePosition(QTextCursor::NextCharacter,
                                 QTextCursor::KeepAnchor,