[clang-tools-extra] [clang-tidy] Add llvm-type-switch-case-types check (PR #177892)

[Yanzuo Liu via cfe-commits]

zwuis wrote:

It would be nice to verify diagnostics with "note" level ("warning" level has been verified).

---

An idea about handling `auto`:

```diff
 TypeSwitch<Pointer *>(base)
-    .Case<T>([](auto x) { ... })
+    .Case([](T *x) { ... })

 TypeSwitch<NonPointer>(base)
-    .Case<T>([](auto x) { ... })
+    .Case([](T x) { ... })
```

Not sure how complex the implementation is so I'm ok with leaving this PR as is.

<details>
<summary>Two possible implementations</summary>

- Find the token `auto` using lexer facilities.
- Use `DeclaratorDecl::getTypeSourceInfo` and `TypeSourceInfo::getTypeLoc()`, then traverse `TypeLoc` to find `TemplateTypeParmTypeLoc` like traversing `ParamBaseType`.

</details>

https://github.com/llvm/llvm-project/pull/177892