feat: add new command to get text

[tandt53]

Hi @Alpaca00 ,

Thanks for your application and solution with dragAndDropWithCommandExtension. It gave me a hint to fix the issue when getting text from Text widget.
Now I want to add a new command getTextWithCommandExtension to get text from Text widget that contains TextSpan widgets as children.

Hope that it will help other like your code did to me.

I added

• 1 widget in the body of main.
• 1 file lib/get_text_command.dart with helper methods to get locator, find element and get the text.
  It works on my local.

demo.mp4

[Alpaca00]

I'm glad the solution was helpful! Your extension for handling TextSpan widgets is a great addition - surely it will benefit others too.