[clang-tidy] Use lexical anon-ns matcher in llvm-prefer-static-over-anonymous-namespace (#148357)
When having this code:
```cpp
namespace {
class MyClassOutOfAnon {
public:
MyClassOutOfAnon();
} // namespace
MyClassOutOfAnon::MyClassOutOfAnon() {}
```
`MyClassOutOfAnon::MyClassOutOfAnon` is located in anonymous namespace
in `DeclContext` but outside anonymous namespace in
`LexicalDeclContext`.
For this check to work correctly, we need to check if definition is
located inside `LexicalDeclContext`.
llvm-project
45f7285d - [clang-tidy] Use lexical anon-ns matcher in llvm-prefer-static-over-anonymous-namespace (#148357)
