Support for setting CIE augmentation strings

[akirilov-arm]

Currently (as of commit 6edacd2) when writing Common Information Entries there is no way to set an augmentation string directly; there is only a way to use a limited set of values indirectly. Support for setting CIE augmentation strings is important when using the Memory Tagging and/or Pointer Authentication extensions to the Arm architecture.

[bjorn3]

Would it make sense to add two bool fields for augmentation characters?

[philipc]

I think these augmentation extensions are something that we need to add explicit support for, rather than letting you directly set the string, because some augmentation characters require special handling. So yes, adding bool fields for these makes sense to me.

It appears we also need to add read support for these.

[akirilov-arm]

Would it make sense to add two bool fields for augmentation characters?

Either option looks fine to me.