TRI-27 emulator: tri_asm.zig and loader.load disagree by two bytes on where the code starts

[dmitrii-f-t27]

Where: tri_asm.zig (the writer) and loader.zig (the reader) at 976df51.

What happens. tri_asm.zig pads its header to twelve bytes, while loader.load reads the code from byte ten.

• A written container loads shifted by two bytes, and its first word decodes from the two padding bytes.
• The owner's tests never load a written container: they copy it to byte 0 and run from word 3.

Source: specs/isa/tri27_bytecode.t27, FINDINGS. The invariant the_writer_header_exceeds_the_loader_header_by_two in the same spec pins the difference.

Expected.

• The writer and the loader agree on the header length.
• A test loads a container written by tri_asm.zig through loader.load.

Vectors. Both are in conformance/trinity/tri27_programs.json:

• load-good: the writer's container is accepted, but the code is taken from byte 10;
• load-native: the ten-byte container the loader expects.

Found while writing the S05 specs of #988 (gHashTag/t27#3581); until now it lived only in the spec's FINDINGS. The vectors are replayed by tools/trinity_tri27.py in gHashTag/t27. Tracked in #1164.