Label support for dd/dq

[RadonCoding]

Currently there's no way to emit anything other than bytes or immediate values. There is no way to emit a label reference directly.

For example, this feature would be useful for building jump tables:

jump_table:
    dq label1
    dq label2
    dq label3

mov rcx, ...
lea rax, [jump_table]
jmp [rax + rcx*8]

Being able to emit labels directly would simplify generating pointer tables without manually calculating offsets.

[MIvanchev]

@RadonCoding This is fully supported with a symbol resolver https://docs.rs/iced-x86/latest/iced_x86/#disassemble-with-a-symbol-resolver.