this is a squash of a few months' hacking, including but not limited to
what eventually got extracted into
https://git.iximeow.net/asmlinator/about/

the path here is generally not historically interesting, and the vast
majority of this diff is very particular static data tables
(BehaviorDigests and implicit operand lists)

`src/long_mode/behavior.rs` will more or less be directly adapted into
versions for x86-32 and x86-16, similar to the instruction decoders.

this is also checked by a new fuzz target

comes with deleting the body of impl Colorize for Operand, because we can reuse the normal operand formatting code

for mem size labels: add one new "BUG" entry at the start of the array
  so `mem_size` does not need to be adjusted before being used to look
  up a string from the `MEM_SIZE_STRINGS` array. it's hard to measure
  the direct benefit of this, but it shrinks codegen size by a bit and
  simplfies a bit of assembly....

for segment reporting changes: stos/scas/lods do not actually need
  special segment override logic. instead, set their use of `es` when
  decoded, if appropriate. this is potentially ambiguous; in non-64bit
  modes the sequence `26aa` would decode as `stos` with explicit `es`
  prefix. this is now identical to simply decoding `aa`, which now also
  reports that there is an explicit `es` prefix even though there is no
  prefix on tne instruction.

  on the other hand, the prefix-reported segment now more accurately
  describes the memory selector through which memory accesses will
  happen. seems ok?