SFC style safe threats

[TheRealGioviok]

TODO: look into this being optimized for speed, especially in inference.

Passed STC:

Test  | threatsrework
Elo   | 2.08 +- 1.66 (95%)
SPRT  | 8.0+0.08s Threads=1 Hash=16MB
LLR   | 2.95 (-2.94, 2.94) [0.00, 3.00]
Games | N: 59878 W: 16033 L: 15674 D: 28171
Penta | [832, 7149, 13669, 7406, 883]

https://ob.cwchess.org/test/1453/

Passed LTC:

Test  | threatsrework
Elo   | 4.12 +- 2.63 (95%)
SPRT  | 40.0+0.40s Threads=1 Hash=64MB
LLR   | 2.95 (-2.94, 2.94) [0.00, 3.00]
Games | N: 19234 W: 4908 L: 4680 D: 9646
Penta | [110, 2217, 4732, 2451, 107]

https://ob.cwchess.org/test/1454/

Bench: 13906139