Add a popup field to edit the default message

[bryanoliveira]

For my use case, I need to quickly edit the default message before sending it to a list of numbers. Therefore I added a message field in the popup to edit the message that was set in the options without saving it.

If you think that's useful for the extension in general, feel free to pull the changes or suggest other ways to do it.

[marcosvrs]

Thanks for your contribution!

I like the idea, but my only concern is that adding this directly to the popup might make it too large. What if we included this field in a collapsible section within the popup?
The main idea of having the message configuration under settings was indeed to save space on the popup, but I'm open to finding a balance that could work for all users.

Let me know your thoughts on this approach, or if you have other suggestions for implementation. Looking forward to further discussion!