Introduce `MockSslInfo`

[sbrannen]

Overview

Since users may wish to create a mock SslInfo instance for use in tests without needing a dedicated mocking library such as Mockito, we should create MockSllInfo in the org.springframework.mock.http.server.reactive package in spring-test, alongside MockServerHttpRequest and MockServerHttpResponse.

Related Issues

• Add support for configuring SslInfo in WebTestClient #35042

[sbrannen]

After further consideration, we have decided to remove the recently introduced MockSslInfo in favor of introducing static factory methods directly in the SslInfo interface. See commit f478f5c for details.