add exhaustive AArch64 decoder/encoder/macro consistency tests

For x86 we have exhaustive tests of every INSTR_CREATE and XINST_CREATE macro with self-consistency tests that the decoder and encoder agree on everything.

For ARM we are still missing this: #1686 (closed).

This issue covers adding such tests for AArch64.

Without these tests, it is fragile to add new XINST_CREATE macros: we have no idea whether they work.