New rule: Prefer %w over literal array syntax for an array of strings.

**VALID EXAMPLES:**
- `STATES = w%(draft open closed)`
- `STATES = brazil["MG"]`
- `STATES = ["draft", 1, "closed"]`

**INVALID EXAMPLES:**
- `STATES = ["draft", "open", "closed"]`
- `STATES = ['draft', 'open', 'closed']`
- `STATES = ["draft", "open"]`
- `STATES = ["draft"]`