Add optional property labelAfter to set label after drop operation

[JorgenLindell]

Summary

Introducing a label to be shown after the drop is completed. Current solution always says "File is uploaded", but in my use case the file should not be uploaded on drop, but rather at a click on a separate button. Then the default text is confusing for the user, as it seems that the upload is already done at that point.

Key Changes

• add (optional) property labelAfter which is used instead of the default one in case it is defined.

Check List

• The changes to the "Readme" file(if needed)
• The changes not breaking any old rule of the library or usage

[Victor-Varghese]

@KarimMokhtar can we merge this PR?

[KarimMokhtar]

@KarimMokhtar can we merge this PR?

Unfortunately, there are required changes that have not been made yet.
If you could make them done it's gonna be great.

[bumi]

pretty please! the "upload another?" text is not matching when the actual submit only happens later and the user has to full out other form fields

[danilloestrela]

@KarimMokhtar what are the requirements needed to finish and merge this PR?