Inline completion brace completion API callback

The brace completion API for inline completions is called after a prediction is returned from the inlineCompletionProvider. As the provider, we don’t have information as to what changes were made with the prediction post brace completion. This negatively impacts our telemetry accuracy. We analyze our telemetry to show better and more useful predictions to the user. Below are some examples:

1. When we send a completion such as }, we have telemetry collected as a completion was shown to the user. But actually, this prediction is not shown to the user because brace completion filters it out since it’s an unbalanced brace.
2. We monitor number of characters in completion vs accept rate (number of completions accepted / number of completions shown). When brace completion makes changes to a prediction returned by us, we don’t have accurate measurements on how many characters were actually shown.

A callback with what completion was shown to user post brace completion would be incredibly helpful for our telemetry accuracy. Alternatively, the ability to call brace completion within the inlineCompletionProvider would also work.

cc @hediet

[juihanamshet1]

Another idea I have is to add an arg in HandleDidShowCompletion which will be set to the insertText after brace completion.

[juihanamshet1]

Awesome, thank you! I found a bug in handleDidShowCompletion, it would be great if we can get it resolved along with this change, it will really augment the accuracy of our telemetry.