message: fix(vue): button semantic
diff: :size="spinnerSize"
  class="loading"
  />
  - <span class="startIcon">
  + <span v-if="$slots.startIcon" class="startIcon">
  <!-- @slot To add icon at the beginning -->
  <slot name="startIcon" />
  </span>
  <!-- @slot To add something, like a text -->
  <slot />
  </span>
  - <span class="endIcon">
  + <span v-if="$slots.endIcon" class="endIcon">
  <!-- @slot To add icon at the end -->
  <slot name="endIcon" />
  </span>
  