Add a specific FRC correction from classical to NNUE

Add a specific FRC correction from classical to NNUE

our net currently is not trained on FRC games, and so doesn't know about the important pattern of a bishop that is cornered in FRC.
This patch introduces a term we have in the classical evaluation for this case, and adds it to the NNUE eval.

Since fishtest doesn't support FRC right now, the patch was tested locally at STC conditions,
starting from the book of FRC starting positions.

Score of master vs patch: 993 - 2226 - 6781  [0.438] 10000

Which corresponds to approximately 40 Elo

The patch passes non-regression testing for traditional chess (where it adds one branch).

passed STC:
https://tests.stockfishchess.org/tests/view/604fa2532433018de7a38b67
LLR: 2.95 (-2.94,2.94) {-1.25,0.25}
Total: 30560 W: 2701 L: 2636 D: 25223
Ptnml(0-2): 88, 2056, 10921, 2133, 82

passed STC also in an earlier version:
https://tests.stockfishchess.org/tests/view/604f61282433018de7a38b4d

closes https://github.com/official-stockfish/Stockfish/pull/3398

No functional change