Add rule `no-useless-children-snippet`

[marekdedic]

Motivation

Any content inside a component tag becomes the children snippet. Thus, If you have a component with a children snippet without parameters, that's unnecessary.

Description

I'd like to add a rule that bans the children snippet if it has no parameters

Examples

<script>
</script>

<!-- ✓ GOOD -->
<Foo>
  {#snippet bar()}
    Hello
  {/snippet}
</Foo>

<Foo>
  {#snippet children(val)}
    Hello {val}
  {/snippet}
</Foo>

<Foo>
  Hello
</Foo>

<!-- ✗ BAD -->
<Foo>
  {#snippet children()}
    Hello
  {/snippet}
</Foo>

Additional comments

No response

[ota-meshi]

Thank you for proposing the rule. SGTM!

Maybe the rule should be a bit clearer. For example, how about the name no-useless-children-snippet?
I think the rule name might confuse users if we later create a rule to report components like this:

{#snippet foo(value)}
  Hello {value}
{/snippet}

<!-- ✗ BAD -->
<Foo>
  {#snippet bar(value)}
    {@render foo(value)}
  {/snippet}
</Foo>

<!-- ✓ GOOD -->
<Foo bar={foo}>
</Foo>

[marekdedic]

Makes sense, renaming! Thanks :)