This fixes the VS16 issues found in this test:
https://ucs-detect.readthedocs.io/sw_results/ghostty.html#ghostty
This is also a more robust way to handle VS15/16 in general.
This commit also changes our propeties to be a packed struct which
reduces its size from 4 bytes to 1 and likewise drops our unicode table
size 4x.
This makes it cleaner to add new sources of table generation and also
avoids inadvertently depending on different modules (despite Zig's lazy
analysis).
This also fixes up terminal to only use our look up tables which avoids
bringing ziglyph in for the terminal module.
