[clang] [Clang][AArch64] Change SME attributes for shared/new/preserved state. (PR #76971)

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https://github.com/rsandifo-arm commented:

Thanks for doing this, looks good!  I've got some initial comments below, but I think they probably repeat for other parts of the patch.  The two main ones are:

* We should consume arguments to attribute keywords iff the attribute is defined to take arguments.
* Even `__arm_preserves("za")` functions are shared-ZA functions.

https://github.com/llvm/llvm-project/pull/76971