Add methods to destroy Groups and Buffer data

[nselliott]

Summary

• This PR is a feature enhancement
• It does the following
  • Fixes Add missing sidre group methods #674
  • Adds missing methods for destroying Groups which will also destroy Buffers if the destruction of a Group and the Views in its subtree cause the Buffer to become detached from all Views.

There already exist View destruction methods such as destroyViewsAndData that implement this destruction of Buffers for this use case. This PR extends the API so that the same thing can be executed on the entire subtree under a Group or set of Groups.

[rhornung67]

Looks good. Thanks @nselliott

[agcapps]

Thank you, Noah.

[kennyweiss]

Thanks for getting these functions in @nselliott !