Separate testing of deprecated @SafeHtml into a separate package

BootStrapValidationTestCase has a method that tests the @SafeHtml annotation that per https://hibernate.atlassian.net/browse/HV-1790 is removed in Hibernate Validator 7.

Move this test method into a subpackage so it can be easily disabled with a JUnit Assume when running with the -Dts.ee9 profile, which test a server that uses HV 7.