[clang] [llvm] [clang] NFC: Remove `{File, Directory}Entry::getName()` (PR #74910)

[via cfe-commits]

GKxxUCAS wrote:

What is the preferred way of knowing the name of a file given its `FileEntry`? In particular I want to check if a certain header `foo.h` is included. Before the removal of `FileEntry::getName()` I could write

```cpp
for (const auto *FE : CI.getPreprocessor().getIncludedFiles())
  if (FE->getName() == "foo.h")
    // do something
```

How can I achieve that now?

https://github.com/llvm/llvm-project/pull/74910