[CINN][Backend Pass Update No.6] Update longlong2int pass (#70462)

* Update longlong2int pass

* Split ll2int to tow passes

* apply cherry pick

* Extract stmt logic from mutator into StmtPass

* Refine comment

* Implement CastLonglong2Int function to convert int64 types to int32 with overflow checks

* Refine

* Rename CastLonglong2Int to TryCastLonglong2Int for clarity and update references

Author: LittleHeroZZZX

paddle/cinn/optim/CMakeLists.txt

@@ -38,7 +38,7 @@ gather_srcs(
   eliminate_common_global_memory_read.cc
   rearrange_load_instruction.cc
   check_tensor_buffer_map.cc
-  longlong2int.cc
+  longlong2int_pass.cc
   vectorize_for_trans.cc)
 
 if(WITH_CUDA OR WITH_ROCM)