aarch64: add E3DSE feature and its associated registers

AArch64 defines new registers for the feature e3dse (Delegated SError
exceptions for EL3): vdisr_el3 and vdisr_el3. e3dse is an Armv9.5-A
feature.

This patch also adds relevant tests. Regression tested on aarch64-none-elf,
and no regression found.