Read/WriteMemory access width parameter addition

Use-case: As an author of embedded tooling, I would like to be able to set granular access width of memory operations, in incrementing bits. This is because many embedded devices have memory areas that can only be accessed using a specific sized memory access operation. The debug adapter can sometimes determine the correct access width however without full context, this is not always possible.

Recommend the following adding to both ReadMemory and WriteMemory:

    /**
     * Specifies the memory access width in bits. Valid values: 8, 16, 32, 64.
     * If not specified, the debugger will determine an appropriate access width.
     */
    width?: number;