feat(reference): add ability to create direct reference

lib/src/reflog.dart

@@ -0,0 +1,52 @@
+import 'dart:ffi';
+import 'bindings/libgit2_bindings.dart';
+import 'bindings/reflog.dart' as bindings;
+import 'reference.dart';
+import 'util.dart';
+
+class RefLog {
+  /// Initializes a new instance of [RefLog] class from provided [Reference].
+  ///
+  /// Throws a [LibGit2Error] if error occured.
+  RefLog(Reference ref) {
+    libgit2.git_libgit2_init();
+
+    final repo = ref.owner;
+    final name = ref.name;
+    _reflogPointer = bindings.read(repo, name);
+  }
+
+  /// Pointer to memory address for allocated reflog object.
+  late final Pointer<git_reflog> _reflogPointer;
+
+  /// Returns the number of log entries in a reflog.
+  int get count => bindings.entryCount(_reflogPointer);
+
+  /// Lookup an entry by its index.
+  ///
+  /// Requesting the reflog entry with an index of 0 (zero) will return
+  /// the most recently created entry.
+  RefLogEntry entryAt(int index) {
+    return RefLogEntry(bindings.entryByIndex(_reflogPointer, index));
+  }
+
+  /// Releases memory allocated for reflog object.
+  void free() {
+    bindings.free(_reflogPointer);
+    libgit2.git_libgit2_shutdown();
+  }
+}
+
+class RefLogEntry {
+  /// Initializes a new instance of [RefLogEntry] class.
+  RefLogEntry(this._entryPointer);
+
+  /// Pointer to memory address for allocated reflog entry object.
+  late final Pointer<git_reflog_entry> _entryPointer;
+
+  /// Returns the log message.
+  String get message => bindings.entryMessage(_entryPointer);
+
+  /// Returns the committer of this entry.
+  Map<String, String> get committer => bindings.entryCommiter(_entryPointer);
+}