More efficient copy object (#6665)

* it compiles

* refactored

* reduce to 4 concurrent chunk upload

* CopyObjectPartHandler

* copy a range of the chunk data, fix offset size in copied chunks

* Update s3api_object_handlers_copy.go

What the PR Accomplishes:
CopyObjectHandler - Now copies entire objects by copying chunks individually instead of downloading/uploading the entire file
CopyObjectPartHandler - Handles copying parts of objects for multipart uploads by copying only the relevant chunk portions
Efficient Chunk Copying - Uses direct chunk-to-chunk copying with proper volume assignment and concurrent processing (limited to 4 concurrent operations)
Range Support - Properly handles range-based copying for partial object copies

* fix compilation

* fix part destination

* handling small objects

* use mkFile

* copy to existing file or part

* add testing tools

* adjust tests

* fix chunk lookup

* refactoring

* fix TestObjectCopyRetainingMetadata

* ensure bucket name not conflicting

* fix conditional copying tests

* remove debug messages

* add custom s3 copy tests

test/s3/copying/test_config.json

@@ -0,0 +1,9 @@
+{
+  "endpoint": "http://localhost:8333",
+  "access_key": "some_access_key1",
+  "secret_key": "some_secret_key1",
+  "region": "us-east-1",
+  "bucket_prefix": "test-copying-",
+  "use_ssl": false,
+  "skip_verify_ssl": true
+}