[ARM] Introduce the v9.5-A architecture version to Arm targets (#78994)

This introduces the Armv9.5-A architecture version to the Arm backend,
following on from the existing implementation for AArch64 targets.

Mode details about the Armv9.5-A architecture version can be found at:
* https://community.arm.com/arm-community-blogs/b/architectures-and-processors-blog/posts/arm-a-profile-architecture-developments-2023
* https://developer.arm.com/documentation/ddi0602/2023-09/