refactor<*>: rewrite all codes...

src/Commands/QueryLFSObject.cs

@@ -0,0 +1,28 @@
+using System;
+
+namespace SourceGit.Commands {
+    /// <summary>
+    ///     取得一个LFS对象的信息
+    /// </summary>
+    public class QueryLFSObject : Command {
+        private Models.LFSObject obj = new Models.LFSObject();
+
+        public QueryLFSObject(string repo, string commit, string path) {
+            Cwd = repo;
+            Args = $"show {commit}:\"{path}\"";
+        }
+
+        public Models.LFSObject Result() {
+            Exec();
+            return obj;
+        }
+
+        public override void OnReadline(string line) {
+            if (line.StartsWith("oid sha256:", StringComparison.Ordinal)) {
+                obj.OID = line.Substring(11).Trim();
+            } else if (line.StartsWith("size")) {
+                obj.Size = int.Parse(line.Substring(4).Trim());
+            }
+        }
+    }
+}