Add memory-region query, enumeration, and scoped protection

Implements VirtualQueryEx + MEMORY_BASIC_INFORMATION wrappers, the immutable MemoryRegion record, the ProtectionScope disposable helper, and MemoryBase.QueryRegion/EnumerateRegions/ChangeProtection. Closes section 1 of add-thread-region-finder.

WhiteMagic/Native/NativeEnums.cs

@@ -156,3 +156,61 @@ public static class ContextFlags
     /// <summary>AMD64: control, integer, and segment registers.</summary>
     public const uint Amd64Full = Amd64Control | Amd64Integer | Amd64Segments;
 }
+
+/// <summary>
+/// Values that describe the state of memory pages returned by <c>VirtualQueryEx</c>.
+/// </summary>
+public enum MemoryState : uint
+{
+    /// <summary>Indicates committed pages for which physical storage has been allocated.</summary>
+    Commit = 0x1000,
+
+    /// <summary>Indicates reserved pages where a range of the virtual address space is reserved without any physical storage being allocated.</summary>
+    Reserve = 0x2000,
+
+    /// <summary>Indicates free pages not accessible to the calling process and available to be allocated.</summary>
+    Free = 0x10000,
+}
+
+/// <summary>
+/// Values that describe the type of memory pages returned by <c>VirtualQueryEx</c>.
+/// </summary>
+public enum MemoryType : uint
+{
+    /// <summary>Indicates that the memory pages within the region are private.</summary>
+    Private = 0x20000,
+
+    /// <summary>Indicates that the memory pages within the region are mapped into the view of a section.</summary>
+    Mapped = 0x40000,
+
+    /// <summary>Indicates that the memory pages within the region are mapped into the view of an image section.</summary>
+    Image = 0x1000000,
+}
+
+/// <summary>
+/// Flags used by <c>CreateToolhelp32Snapshot</c> to specify the portions of the system to include in the snapshot.
+/// </summary>
+[Flags]
+public enum SnapshotFlags : uint
+{
+    /// <summary>Enumerate the heap list.</summary>
+    HeapList = 0x00000001,
+
+    /// <summary>Enumerate the process list.</summary>
+    Process = 0x00000002,
+
+    /// <summary>Enumerate the thread list.</summary>
+    Thread = 0x00000004,
+
+    /// <summary>Enumerate the module list.</summary>
+    Module = 0x00000008,
+
+    /// <summary>Enumerate the 32-bit module list for the specified process.</summary>
+    Module32 = 0x00000010,
+
+    /// <summary>Include all processes and threads in the system.</summary>
+    All = 0x0000001F,
+
+    /// <summary>Indicate that the snapshot handle is to be inheritable.</summary>
+    Inherit = 0x80000000,
+}