ARM64: print canonical syntax for add/sub (imm) instructions.

Since these instructions only accept a 12-bit immediate, possibly shifted left
by 12, the canonical syntax used by the architecture reference manual is "#N {,
lsl #12 }". We should accept an immediate that has already been shifted, (e.g.

Also, print a comment giving the full addend since it can be helpful.
ARM64: hexify printing various immediate operands

This is mostly aimed at the NEON logical operations and MOVI/MVNI (since they
accept weird shifts which are more naturally understandable in hex notation).

Also changes BRK/HINT etc, which is probably a neutral change, but easier than
the alternative.
ARM64: use hex immediates for movz/movk instructions

Since these are mostly used in "lsl #16", "lsl #32", "lsl #48" combinations to
piece together an immediate in 16-bit chunks, hex is probably the most
appropriate format.