improve auto generated conditional class names

[jantimon]

right now we generate class names for binary expressions

e.g.

const Button styled.button`
  ${({$primary}) => $primary ? css`color:red` : css`color:blue`};
`

becomes Button__primary or Button__not-primary

we should also extend that for string and number values

e.g.:

const Button styled.button`
  ${({$variant}) => $variant === 'primary' ? css`color:red` : css`color:blue`};
`

could become Button__variant-primary or Button__variant-not-primary