Spring Security Remove sitemesh dependency

Summary

Our build currently depends on sitemesh, but it hasn't been updated in a very long time. We should remove it from our builds and instead rely on thymeleaf support.

Comment From: vcvitaly

@rwinch is the issue still available to contribute? I'd link to pick it up

Comment From: rwinch

Thank your for volunteering @valery1707 The issue is yours!

Comment From: SeifMostafa

Is it still available?

Comment From: rwinch

Samples have moved to an external location https://github.com/spring-projects/spring-security-samples