[clang] [Clang] NFC: Move Arm type attributes to separate trailing object. (PR #78424)

[Erich Keane via cfe-commits]

https://github.com/erichkeane approved this pull request.

This way of moving these further away is alright with me.  If Aaron is OK with it, than I am too.  So please wait for his approval too.

https://github.com/llvm/llvm-project/pull/78424