single/multiple-choices: support for compile message with option label

[andersonba]

- name: colors
  options:
    - label: Black
      value: '#000'
    - label: White
      value: '#FFF'
 
- message: {{colors}} are colors

Result:

#000,#FFF are colors

Expected:

Black,White are colors

[andersonba]

SingleChoice usage

  ...
  options:
    - label: Black
      value: #000
    - label: White
      value: #fff

{{ color }} or {{ color.value }}
#000

{{ color.label }}
Black

MultipleChoice usage

  ...
  options:
    - label: One
      value: 1
    - label: Two
      value: 2

{{ numbers }}
1,2

{{ numbers.0.label }}
One

{{ numbers.0 }} or {{ numbers.0.value }}
1