增加圖片上傳中的狀態提示

[Yukaii]

Describe the bug A clear and concise description of what the bug is. 請清晰詳細的描述這個問題

To Reproduce Steps to reproduce the behavior: 列出可以重現問題的步驟：

1. Go to '...'
2. Click on '....'
3. Scroll down to '....'
4. See error

Expected behavior A clear and concise description of what you expected to happen.

Screenshots If applicable, add screenshots to help explain your problem. 截圖

Desktop (please complete the following information):

• OS: [e.g. iOS]
• Browser [e.g. chrome, safari]
• Version [e.g. 22]

Smartphone (please complete the following information):

• Device: [e.g. iPhone6]
• OS: [e.g. iOS8.1]
• Browser [e.g. stock browser, safari]
• Version [e.g. 22]

Additional context

Add any other context about the problem here.

[Yukaii]

補充上傳圖片時的按鈕，應在圖片上傳時，顯示為「上傳中......」

[Yukaii]

https://github.com/Disfactory/frontend/blob/5a70e152af41ad9350c246de695b9907193b1f17/src/components/UpdateFactorySteps.vue#L62-L74

參考 vue template uploading 的判斷，顯示上傳中或 submitText

https://github.com/Disfactory/frontend/blob/d609f9e42e8983cc4552537e2808e2962347f515/src/components/ImageUploadForm.vue#L59-L63