[LiveComponent] Improve form validation error messages in exceptions

[PierreCapel]

Q	A
Bug fix?	no
New feature?	yes
Deprecations?	no
Documentation?	no
License	MIT

When calling $this->submitForm() manually in a LiveAction, if validation fails, an UnprocessableEntityHttpException is thrown. Currently, this exception contains a generic message: "Form validation failed in component."

This makes it difficult to debug failures in automated tests or during development, especially with large forms or collections, as we need to manually inspect the form state to find the cause.

This PR adds the the full field path and the specific violation message in the exception.

Example output:

Form validation failed:
blog_post_form.title: This value should not be blank.
blog_post_form.content: This value is too short. It should have 100 characters or more.
blog_post_form.comments.0.text: This value should not be blank.

[MrYamous]

Suggested change

	$errors = [];
	foreach ($form->getErrors() as $error) {
	$label = '' !== $prefix ? $prefix : 'form';
	$errors = [];
	$label = '' !== $prefix ? $prefix : 'form';
	foreach ($form->getErrors() as $error) {

It looks safe to put this outside the loop