EditorBatchProcessor.cs

using System;
using System.Collections.Generic;
using System.Threading.Tasks;
using UnityEditor;
using UnityEngine;

namespace Mewlist
{
    public class EditorBatchProcessor
    {
        private List<Func<Task>> tasks = new List<Func<Task>>();
        private bool frameProgression = false;

        public async Task Run()
        {
            EditorApplication.update += OnUpdate;
            try
            {
                await Process();
            }
            catch (Exception e)
            {
                Debug.Log(e);
            }
            EditorApplication.update -= OnUpdate;
        }

        public void Add(Func<Task> action) => tasks.Add(action);
        public void SelectObject(GameObject go) => Add(async () => Selection.activeObject = go);

        private async Task Process()
        {
            foreach (var action in tasks)
            {
                Debug.Log("[EditorBatchProcessor] " + action.Method.Name + "()");
                await action();
                await WaitForNextFrame();
            }
        }

        private void OnUpdate() => frameProgression = true;

        private async Task WaitForNextFrame()
        {
            frameProgression = false;
            while (!frameProgression) await Task.Delay(100);
        }
    }
}

SampleCode

// 使い方

async Task ProcessAsset()
{
    var processor = new EditorBatchProcessor();

    // 何らかのゲームオブジェクトへのコンポーネント登録操作
    var go = new GameObject();
    var component = go.AddComponent<HogeComponent>();

    async Task FirstStep()
    {
        // 任意のEditor拡張処理
    }
    async Task LastStep()
    {
        // インスペクタ表示後の処理
    }

    // 処理を手続き的に登録
    processor.Add(FirstStep)
    processor.SelectObject(go); // インスペクタを一度表示する
    processor.Add(LastStep)
    await processor.Run();
}