fix(ui): QSelect missing classes that show up as "[object Object]"

[hawkeye64]

QSelect is missing many classes that come from computed:

missing:

      fieldClass: computed(() =>
        `q-select q-field--auto-height q-select--with${ props.useInput !== true ? 'out' : '' }-input`
        + ` q-select--with${ props.useChips !== true ? 'out' : '' }-chips`
        + ` q-select--${ props.multiple === true ? 'multiple' : 'single' }`
      ),