[next] fix(NcCheckboxContent): correctly check default slot

[raimund-schluessler]

☑️ Resolves

• Fixes the detection whether NcCheckboxContent has text. Before, it would always be true leading to a wrong padding right.

🖼️ Screenshots

🏚️ Before	🏡 After

[raimund-schluessler]

Isn't it fixable on NcCheckboxRadioSwitch's side same as in some other component? To avoid tripple rendering.

<template v-if="!!$slots.default" #default>
  <slot />
</template>

Yes, of course. Thanks for remembering that! Fixed it.