Please describe what the rule should do:

The rule should warn when a custom directive is used, but not imported. The rule should also accept some kind ofignore option to avoid false positives with globally-registered custom directives.

What category should the rule belong to?

• Enforces code style (layout)
• Warns about a potential error (problem)
• Suggests an alternate way of doing something (suggestion)
• Other (please specify:)

Provide 2-3 code examples that this rule should warn about:

Should warn on:

<template>  <inputv-focus></template><script setup>// vFocus is not imported or defined anywhere</script>

<template>  <av-sref="someValue"><!-- anchor contents-->  </a></template><script setup>// vSref is not imported or defined anywhere</script>

Should not warn on:

<template>  <inputv-focus></template><script setup>importvFocusfrom'../path/to/vFocus';</script>

<template>  <av-sref="someValue"><!-- anchor contents-->  </a></template><script setup>importvSreffrom'../path/to/vSref';</script>

Additional context

There is a runtime warning in the browser console, but it would be cool if we can catch these issues when linting too.

[Vue warn]: Failed to resolve directive: sref