apacheGH-41034: [C++][FS][Azure] Adjust DeleteDir/DeleteDirContents/G…

…etFileInfoSelector behaviors against Azure for generic filesystem tests (apache#41068)

### Rationale for this change

They are failing:

```text
[  FAILED  ] TestAzureHierarchicalNSGeneric.DeleteDir
[  FAILED  ] TestAzureHierarchicalNSGeneric.DeleteDirContents
[  FAILED  ] TestAzureHierarchicalNSGeneric.GetFileInfoSelector
```

### What changes are included in this PR?

* `DeleteDir()`: Check not a directory case
* `DeleteDirContents()`: Check not a directory case
* `GetFileInfoSelector()`:
  * Add not a directory check for input
  * Add support for returning metadata for directory 

### Are these changes tested?

Yes.

### Are there any user-facing changes?

Yes.
* GitHub Issue: apache#41034

Authored-by: Sutou Kouhei <kou@clear-code.com>
Signed-off-by: Sutou Kouhei <kou@clear-code.com>

cpp/src/arrow/filesystem/azurefs_test.cc

@@ -392,7 +392,7 @@ class TestGeneric : public ::testing::Test, public GenericFileSystemTest {
   bool allow_move_dir() const override { return false; }
   bool allow_move_file() const override { return true; }
   bool allow_append_to_file() const override { return true; }
-  bool have_directory_mtimes() const override { return false; }
+  bool have_directory_mtimes() const override { return true; }
   bool have_flaky_directory_tree_deletion() const override { return false; }
   bool have_file_metadata() const override { return true; }
   // calloc() used in libxml2's xmlNewGlobalState() is detected as a
@@ -429,6 +429,8 @@ class TestAzuriteGeneric : public TestGeneric {
  protected:
   // Azurite doesn't support moving files over containers.
   bool allow_move_file() const override { return false; }
+  // Azurite doesn't support directory mtime.
+  bool have_directory_mtimes() const override { return false; }
   // DeleteDir() doesn't work with Azurite on macOS
   bool have_flaky_directory_tree_deletion() const override {
     return env_->HasSubmitBatchBug();
@@ -449,6 +451,8 @@ class TestAzureFlatNSGeneric : public TestGeneric {
  protected:
   // Flat namespace account doesn't support moving files over containers.
   bool allow_move_file() const override { return false; }
+  // Flat namespace account doesn't support directory mtime.
+  bool have_directory_mtimes() const override { return false; }
 };
 
 class TestAzureHierarchicalNSGeneric : public TestGeneric {