Bug 404076 - s390x: Implement z14 vector instructions

Bug 404076 - s390x: Implement z14 vector instructions

Implement the new instructions/features that were added to z/Architecture
with the vector-enhancements facility 1.  Also cover the instructions from
the vector-packed-decimal facility that are defined outside the chapter
"Vector Decimal Instructions", but not the ones from that chapter itself.

For a detailed list of newly supported instructions see the updates to
`docs/internals/s390-opcodes.csv'.

Since the miscellaneous instruction extensions facility 2 was already
addressed by Bug 404406, this completes the support necessary to run
general programs built with `--march=z14' under Valgrind.  The
vector-packed-decimal facility is currently not exploited by the standard
toolchain and libraries.