Implement generic LUT-based elementwise operator

Reimplement QU8 Leaky ReLU and QU8 Sigmoid as generic LUT-based elementwise
operators

PiperOrigin-RevId: 395645459
diff --git a/CMakeLists.txt b/CMakeLists.txt
index a4e254d..32982ca 100755
--- a/CMakeLists.txt
+++ b/CMakeLists.txt
@@ -175,12 +175,11 @@
   src/operators/fully-connected-nc.c
   src/operators/global-average-pooling-ncw.c
   src/operators/global-average-pooling-nwc.c
-  src/operators/leaky-relu-nc.c
+  src/operators/lut-elementwise-nc.c
   src/operators/max-pooling-nhwc.c
   src/operators/prelu-nc.c
   src/operators/resize-bilinear-nchw.c
   src/operators/resize-bilinear-nhwc.c
-  src/operators/sigmoid-nc.c
   src/operators/softmax-nc.c
   src/operators/unary-elementwise-nc.c
   src/operators/unpooling-nhwc.c)