Improve URL validation

[ernilambar]

We have pretty basic URL validation currently:

function is_valid_url( $url ) {
	return filter_var( $url, FILTER_VALIDATE_URL ) === $url && str_starts_with( $url, 'http' );
}

We frequently get this type of URL with duplicated protocol but our function does not detect that.

https://http://example.com/

We could improve the is_valid_url() function to handle such edge case.