This PR improves the `edit prediction: Capture Example` in several ways:
* fixed bugs in how the uncommitted diff was calculated
* added a `edit_predictions.examples_dir` setting that can be set in
order to have the action automatically save examples into the given
folder
* moved the action into the `edit_predictions` crate, in preparation for
collecting this data passively from end users, when they have opted in
to data sharing, similar to what we did for Zeta 1
Release Notes:
- N/A
07ada58466