[clang][Sema] Move the initializer lifetime checking code from SemaInit.cpp to a new place, NFC (llvm#96758)

This is a refactoring change for better code isolation and reuse, the
first step to extend it for assignments.

Author: hokein

clang/lib/Sema/CMakeLists.txt

@@ -15,6 +15,7 @@ clang_tablegen(OpenCLBuiltins.inc -gen-clang-opencl-builtins
 
 add_clang_library(clangSema
   AnalysisBasedWarnings.cpp
+  CheckExprLifetime.cpp
   CodeCompleteConsumer.cpp
   DeclSpec.cpp
   DelayedDiagnostic.cpp