[clang] [NFC][Clang][Sema] Apply Rule of Three to various classes (PR #174516)

[Shafik Yaghmour via cfe-commits]

shafik wrote:

> The changes LGTM as far as they go, but we don't have any coding standard requirement for a rule of three (five, zero, etc) and these changes are a noop. If we're going to have tools which enforce a rule like this, should we change the coding standard to mention following the rule?

Yeah that might be a good idea. It is a pretty common sense rule, if you have a resource/count/flag/etc you are specially managing on construction/destruction you should either implement copy or explicitly delete them.

https://github.com/llvm/llvm-project/pull/174516