Notify UserData that view state should be preserved.

This is only active when a trace is loaded from a file (and state should
be persistent for future sessions using this trace), or when state is
saved to a file (so that future sessions will use current state).

No state is preserved by default, i.e. when the trace was not saved to a
file.

server/TracyUserData.cpp

@@ -10,6 +10,7 @@ namespace tracy
 constexpr auto FileDescription = "description";
 
 UserData::UserData()
+    : m_preserveState( false )
 {
 }
 
@@ -52,6 +53,11 @@ bool UserData::SetDescription( const char* description )
     return true;
 }
 
+void UserData::StateShouldBePreserved()
+{
+    m_preserveState = true;
+}
+
 FILE* UserData::OpenFile( const char* filename, bool write )
 {
     const auto path = GetSavePath( m_program.c_str(), m_time, filename, write );