[clang] NFC: Make clang resource headers an interface library (PR #88317)

[Alexander Yermolovich via cfe-commits]

ayermolo wrote:

I am seeing a cmake error in one of the build steps in our enviroment:
```
CMake Error at CMakeLists.txt:86 (get_property):
  get_property could not find TARGET clang-resource-headers.  Perhaps it has
  not yet been created.
  ```
  Reverting this diff internally made build pass.
  I'll try to create small repro, but in meantime can you revert?

https://github.com/llvm/llvm-project/pull/88317