Add a memoryType: assembly to Variable #495

Use case

For pointers, the memoryReference attached to a pointer points to the corresponding memory.
Currently, this memory is shown in VS-Code in the hex-editor.

However, for function pointers, it would be more ergonomic to show this memory area in the disassembly view.

Proposal

type MemoryType = 'raw' | 'assembly';

interface Variable {
  // ...
  
  /**
   * A memory reference associated with this variable.
   * For pointer type variables, this is generally a reference to the memory
   * address contained in the pointer.
   * For executable data, this reference may later be used in a `disassemble`
   * request.
   * This attribute may be returned by a debug adapter if corresponding
   * capability `supportsMemoryReferences` is true.
   */
  memoryReference?: string;
  /**
   * Determines the type of memory which this memory reference is
   * referring to.
   */
  memoryType?: MemoryType;
}

// Similar for `EvaluateResponse`, `Output`, `SetExpressionResponse`

The UI could then open either the disassembly or the hex-editor for the given memoryReference, as appropriate. (Or even offer a choice to the user whether to use the disassembly or the hex-editor view).

This might also be useful in combination with microsoft/vscode#197287, where extensions might introduce own, customMemoryType. E.g., I could imagine other extensions to contribute a PNG-viewer which allows viewing PNGs directly from within the program's memory. (But I don't have any particular use case in that direction. My main motivation here is to get better default-behavior for function pointers)