Fix SpinBox will reset unsubmitted text when redrawing

[jsjtxietian]

This should fix #79507

As I mentioned in the issue, this commit added _update_text() to NOTIFICATION_DRAW. And insided _update_text(), it uses the shared range value to update the line_edit's text, but the value will override the unsubmited user's input.

Originally this commit makes sense because user may call set_value_no_signal which will directly change shared range's value, but when a user input some text and then triggered NOTIFICATION_DRAW, this could be wrong and cause this bug.

So we will encounter a situation where we have two sources of value that need to consider in _update_text, one from script like set_value_no_signal which directly change range's value , one from user's uncommited input reflected in line_edit compoment.

Basically what my fix do is that it trys to remember the last_updated_text, and when the value get from shared range equals this last_updated_text but not euqal to line_edit's current value, just return to keep line_edit's current value. That being saied, when a user is inputing something and some script called set_value_no_signal at the same time, this code will keep the shared range's value instead of user's input.

It should work in most cases, I know this is not the best fix, but I think it is less invasive in this way. I would appreciate any feedback or alternative suggestions.

[KoBeWi]

When you press Escape to unfocus the SpinBox, anything you wrote will remain.

[jsjtxietian]

When you press Escape to unfocus the SpinBox, anything you wrote will remain.

I guess this is not the expected behaviour? If the user do not turn on autosave, I guess it should drop the content after unfocus?

[KoBeWi]

Yes, it's a bug. You can write some invalid non-numeric value and it will linger.

[akien-mga]

Thanks!