Set class and id for components

[pandaulait]

Is your feature request related to a problem? Please describe.
There were cases where I wanted to set a class or id on the component itself, as shown below

<ButtonComponent class="mt-10"></ButtonComponent>

<SectionComponent id="about"></SectionComponent>

Describe the solution you'd like
I'm implementing the following as a workaround right now, so it would be easier to use if you could specify class and id to the component

<SectionComponent>
  <div id="about">...  </div>
</SectionComponent>

However, in order to consider the pros and cons of this issue, we would need to review the current specification that allows multiple elements to be set in the root of a component

<!-- SectionComponent.spear-- >
<div></div>
<div></div>
...

↓

<!-- SectionComponent.spear-- >
<div></div>