target/arm: Implement the SETG* instructions

The FEAT_MOPS SETG* instructions are very similar to the SET*
instructions, but as well as setting memory contents they also
set the MTE tags. They are architecturally required to operate
on tag-granule aligned regions only.

Signed-off-by: Peter Maydell <peter.maydell@linaro.org>
Reviewed-by: Richard Henderson <richard.henderson@linaro.org>
Message-id: 20230912140434.1333369-10-peter.maydell@linaro.org