(WIP) Add cpu execution mode for abs kernel (jit mode)

[zouzias]

To reproduce

make compile_cpu_abs
g++-15 -fPIC -shared -D__CPU_SIM -std=c++20 \
        -Icsrc/kernel \
        -I/usr/local/Ascend/cann-9.0.0/include \
        -D_FORTIFY_SOURCE=2 -Wno-macro-redefined -Wno-ignored-attributes \
        -fstack-protector-strong \
        csrc/kernel/kernel_abs.cpp \
        -o libkernel_abs.so

python run_abs_cpu.py 
Loaded library from /home/zouzias/github-repos/pto-kernels/libkernel_abs.so
Is all close? True
tensor([0.0276, 0.6040, 1.5723, 1.1709, 2.3477, 0.2180, 0.5034, 0.5659, 0.7349,
        1.4131], dtype=torch.float16)
tensor([0.0276, 0.6040, 1.5723, 1.1709, 2.3477, 0.2180, 0.5034, 0.5659, 0.7349,
        1.4131], dtype=torch.float16)