GH-50311: [C++] KeyValueMetadata::Delete returns IndexError instead of crashing due to seg fault (#50322)

* The Delete function now catches out of bound index and does not throw a segmentation fault.

### Rationale for this change
The `KeyValueMetadata::Delete(int64_t index)` never checked for out of bounds value of `index`, & if `index` was out of bounds, then a seg fault was thrown by the program and it aborted.

### What changes are included in this PR?
The `KeyValueMetadata::Delete(int64_t index)` now returns a IndexError for out of bounds values of `index`

### Are these changes tested?
Yes, CI tests pass on my fork

### Are there any user-facing changes?
No API changes

* GitHub Issue: #50311

Lead-authored-by: OmBiradar <ombiradar04@gmail.com>
Co-authored-by: Om Biradar <ombiradar04@gmail.com>
Co-authored-by: Antoine Pitrou <pitrou@free.fr>
Signed-off-by: Antoine Pitrou <antoine@python.org>

Author: OmBiradar

cpp/src/arrow/util/key_value_metadata.cc

@@ -100,6 +100,12 @@ Result<std::string> KeyValueMetadata::Get(std::string_view key) const {
 }
 
 Status KeyValueMetadata::Delete(int64_t index) {
+  if (ARROW_PREDICT_FALSE(index < 0 || index >= static_cast<int64_t>(keys_.size()))) {
+    return Status::IndexError("KeyValueMetadata::Delete: index ", index,
+                              " is out of bounds for metadata "
+                              "of size ",
+                              keys_.size());
+  }
   keys_.erase(keys_.begin() + index);
   values_.erase(values_.begin() + index);
   return Status::OK();

cpp/src/arrow/util/key_value_metadata_test.cc

@@ -187,6 +187,26 @@ TEST(KeyValueMetadataTest, Delete) {
     ASSERT_OK(metadata.Delete(3));
     ASSERT_TRUE(metadata.Equals(
         KeyValueMetadata({"aa", "bb", "dd", "ff", "gg"}, {"1", "2", "4", "6", "7"})));
+
+    std::string expected_error_message =
+        "Index error: KeyValueMetadata::Delete: index -1 is out of bounds for metadata "
+        "of size 5";
+    ASSERT_RAISES_WITH_MESSAGE(IndexError, expected_error_message, metadata.Delete(-1));
+    expected_error_message =
+        "Index error: KeyValueMetadata::Delete: index 7 is out of bounds for metadata "
+        "of size 5";
+    ASSERT_RAISES_WITH_MESSAGE(IndexError, expected_error_message, metadata.Delete(7));
+
+    ASSERT_OK(metadata.Delete(4));
+    ASSERT_OK(metadata.Delete(3));
+    ASSERT_OK(metadata.Delete(2));
+    ASSERT_OK(metadata.Delete(1));
+    ASSERT_OK(metadata.Delete(0));
+
+    expected_error_message =
+        "Index error: KeyValueMetadata::Delete: index 7 is out of bounds for metadata "
+        "of size 0";
+    ASSERT_RAISES_WITH_MESSAGE(IndexError, expected_error_message, metadata.Delete(7));
   }
   {
     KeyValueMetadata metadata(keys, values);