apacheGH-39297: [C++][FS]: Inform caller of container not-existing when checking for HNS support (apache#39298)

### Rationale for this change

An operation checking for Hierarchical Namespace support shouldn't fail completely when the reason for the check failing is the container not existing. We can allow the caller to decide what to do in that situation by returning a result that indicates the check didn't succeed because the container doesn't exist.

### What changes are included in this PR?

 - Removal of the `azurefs_intern.h/cc` files
 - Implementation of the check as a free-function instead of a class
 - Memoization of the result in the `AzureFileSystem` class

### Are these changes tested?

Yes. The tests were improved to cover all cases.
* Closes: apache#39297

Authored-by: Felipe Oliveira Carvalho <[email protected]>
Signed-off-by: Felipe Oliveira Carvalho <[email protected]>

Author: felipecrv

cpp/src/arrow/CMakeLists.txt

@@ -506,8 +506,8 @@ if(ARROW_FILESYSTEM)
        filesystem/util_internal.cc)
 
   if(ARROW_AZURE)
-    list(APPEND ARROW_SRCS filesystem/azurefs.cc filesystem/azurefs_internal.cc)
-    set_source_files_properties(filesystem/azurefs.cc filesystem/azurefs_internal.cc
+    list(APPEND ARROW_SRCS filesystem/azurefs.cc)
+    set_source_files_properties(filesystem/azurefs.cc
                                 PROPERTIES SKIP_PRECOMPILE_HEADERS ON
                                            SKIP_UNITY_BUILD_INCLUSION ON)
   endif()