Editor code: tidy up BOOLs,NULLs and overrides pt3.

A few 'typedefs' replaced by 'using's
This shouldn't have any functional changes at all, just c++17 modernization
It's a part 3 of a split #2847

Signed-off-by: Nemerle <nemerle5+git@gmail.com>

Code/Editor/TrackView/TrackViewFindDlg.cpp

@@ -24,13 +24,13 @@ AZ_POP_DISABLE_DLL_EXPORT_MEMBER_WARNING
 // CTrackViewFindDlg dialog
 
 
-CTrackViewFindDlg::CTrackViewFindDlg(const char* title, QWidget* pParent /*=NULL*/)
+CTrackViewFindDlg::CTrackViewFindDlg(const char* title, QWidget* pParent /*=nullptr*/)
     : QDialog(pParent)
     , ui(new Ui::TrackViewFindDlg)
 {
     setWindowTitle(title);
 
-    m_tvDlg = 0;
+    m_tvDlg = nullptr;
     m_numSeqs = 0;
 
     ui->setupUi(this);