Remove remaining CRT PAL wrappers and enable including standard headers in the CoreCLR build (#98336)

- Remove malloc-family PAL and update callsites that might get passed 0 to bump up to 1.
- Move `getenv` usage to use the `PAL` function directly when on non-Windows (to preserve the existing behavior).
- Remove other remaining CRT PAL shims
- Remove header shims and enable building with the CRT and STL headers across the product, with various build fixes required (mostly around using the standard min/max definitions)

eng/native/configurecompiler.cmake

@@ -28,7 +28,6 @@ if (CLR_CMAKE_HOST_UNIX)
         add_compile_options(-Wno-null-conversion)
         add_compile_options(-glldb)
     else()
-        add_compile_options($<$<COMPILE_LANGUAGE:CXX>:-Werror=conversion-null>)
         add_compile_options(-g)
     endif()
 endif()

eng/native/functions.cmake

@@ -220,6 +220,12 @@ endfunction(convert_to_absolute_path)
 function(preprocess_file inputFilename outputFilename)
   get_compile_definitions(PREPROCESS_DEFINITIONS)
   get_include_directories(PREPROCESS_INCLUDE_DIRECTORIES)
+  get_source_file_property(SOURCE_FILE_DEFINITIONS ${inputFilename} COMPILE_DEFINITIONS)
+  
+  foreach(DEFINITION IN LISTS SOURCE_FILE_DEFINITIONS)
+    list(APPEND PREPROCESS_DEFINITIONS -D${DEFINITION})
+  endforeach()
+
   if (MSVC)
     add_custom_command(
         OUTPUT ${outputFilename}