Missing config schema

Problem/Motivation

Every Webform handler has to have a config schema, otherwise importing/saving its configuration fails when config schema checker service is available. E.g.: Drupal\Core\Config\Schema\SchemaIncompleteException: Schema errors for webform.webform.foo with the following errors: webform.webform.fooo:handlers.send_multiple_emails.settings.states missing schema,

Steps to reproduce

Define config schema for the send_multiple_emails Webform handler. E.g: https://git.drupalcode.org/project/webform/-/blob/6.2.3/config/schema/we...

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes