feat: PDB import via RawPDB, no msdia140.dll dependency

Replace DIA SDK COM-based PDB importer with RawPDB (MolecularMatters)
which reads PDB files directly via memory-mapped I/O. Adds File menu
"Import PDB..." dialog with type filtering, selection, and progress.

- Vendor raw_pdb into third_party/
- Two-phase API: enumeratePdbTypes() + importPdbSelected()
- Full recursive import of structs/unions/arrays/pointers/bitfields
- PDB import dialog with name filter, select-all, type count
- Benchmark: 1654 types from ntkrnlmp.pdb in 16ms
- Reorganize import/export files into src/imports/

third_party/raw_pdb/src/Examples/ExampleTimedScope.h

@@ -0,0 +1,22 @@
+// Copyright 2011-2022, Molecular Matters GmbH <office@molecular-matters.com>
+// See LICENSE.txt for licensing details (2-clause BSD License: https://opensource.org/licenses/BSD-2-Clause)
+
+#include "Foundation/PDB_Macros.h"
+#include <chrono>
+
+
+class TimedScope
+{
+public:
+	explicit TimedScope(const char* message);
+
+	void Done(void) const;
+	void Done(size_t count) const;
+
+private:
+	double ReadMilliseconds(void) const;
+
+	const std::chrono::high_resolution_clock::time_point m_begin;
+
+	PDB_DISABLE_COPY_MOVE(TimedScope);
+};