Remove unused type_is_pod function
Implement `has_dtor` method in TypeContents
Don't allow static items with `Drop`

Partially addresses #10577
auto merge of #11979 : FlaPer87/rust/static, r=cmr

This pull request partially addresses the 2 issues listed before. As part of the work required for this PR, `NonCopyable` was completely removed.

This PR also replaces the content of `type_is_pod` with `TypeContents::is_pod`, although `type_is_content` is currently not being used anywhere. I kept it for consistency with the other functions that exist in this module.

cc #10834
cc #10577