fix multiple submit issue. now show CircularProgressIndicator instead…

[poriya219]

fix multiple submit issue. now show CircularProgressIndicator instead…

📜 Description

fix multiple submit issue. now show CircularProgressIndicator instead of TextButton when submitting.

💡 Motivation and Context

this changes fix this issue:
#345

💚 How did you test it?

I created a test flutter app and used this updated package in this app and everything worked. also, I ran a web server from the example app in the repository, and everything worked.

📝 Checklist

• [ x] I reviewed submitted code
• [ x] I added tests to verify changes
• [ x] I updated the docs if needed
• [x ] All tests passing
• [ x] No breaking changes

🔮 Next steps

[Akimskate]

The changes are working correctly on my side. Kindly review and proceed with merging this pull request.

[roylenz]

I also needed something similar, so I copied the string feedback widget and modified it to have the loading bool in the state.

I think this is a really good change to have but in my opinion modifying the feedbackBuilder signature is problematic as it creates a breaking change to everyone using it so far, and this change shouldn't really affect people that use the feedbackBuilder parameter as they probably have loading indicators of their own.