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/PDB_DirectMSFStream.h

@@ -0,0 +1,84 @@
+// 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)
+
+#pragma once
+
+#include "Foundation/PDB_Macros.h"
+
+
+// https://llvm.org/docs/PDB/index.html#the-msf-container
+// https://llvm.org/docs/PDB/MsfFile.html
+namespace PDB
+{
+	// provides direct access to the data of an MSF stream.
+	// inherently thread-safe, the stream doesn't carry any internal offset or similar.
+	// trivial to construct.
+	// slower individual reads, but pays off when not all data of a stream is needed.
+	class PDB_NO_DISCARD DirectMSFStream
+	{
+	public:
+		DirectMSFStream(void) PDB_NO_EXCEPT;
+		explicit DirectMSFStream(const void* data, uint32_t blockSize, const uint32_t* blockIndices, uint32_t streamSize) PDB_NO_EXCEPT;
+
+		PDB_DEFAULT_MOVE(DirectMSFStream);
+
+		// Reads a number of bytes from the stream.
+		void ReadAtOffset(void* destination, size_t size, size_t offset) const PDB_NO_EXCEPT;
+
+		// Reads from the stream.
+		template <typename T>
+		PDB_NO_DISCARD inline T ReadAtOffset(size_t offset) const PDB_NO_EXCEPT
+		{
+			T data;
+			ReadAtOffset(&data, sizeof(T), offset);
+			return data;
+		}
+
+		// Returns the block size of the stream.
+		PDB_NO_DISCARD inline uint32_t GetBlockSize(void) const PDB_NO_EXCEPT
+		{
+			return m_blockSize;
+		}
+
+		// Returns the size of the stream.
+		PDB_NO_DISCARD inline uint32_t GetSize(void) const PDB_NO_EXCEPT
+		{
+			return m_size;
+		}
+
+	private:
+		friend class CoalescedMSFStream;
+
+		struct IndexAndOffset
+		{
+			uint32_t index;
+			uint32_t offsetWithinBlock;
+		};
+
+		// Returns the block index and offset within the block that correspond to the given offset.
+		PDB_NO_DISCARD IndexAndOffset GetBlockIndexForOffset(uint32_t offset) const PDB_NO_EXCEPT;
+
+		// Returns the offset into the data that corresponds to the given indices and offset within a block.
+		PDB_NO_DISCARD size_t GetDataOffsetForIndexAndOffset(const IndexAndOffset& indexAndOffset) const PDB_NO_EXCEPT;
+
+		// Provides read-only access to the memory-mapped data.
+		PDB_NO_DISCARD inline const void* GetData(void) const PDB_NO_EXCEPT
+		{
+			return m_data;
+		}
+
+		// Provides read-only access to the block indices.
+		PDB_NO_DISCARD inline const uint32_t* GetBlockIndices(void) const PDB_NO_EXCEPT
+		{
+			return m_blockIndices;
+		}
+
+		const void* m_data;
+		const uint32_t* m_blockIndices;
+		uint32_t m_blockSize;
+		uint32_t m_size;
+		uint32_t m_blockSizeLog2;
+
+		PDB_DISABLE_COPY(DirectMSFStream);
+	};
+}