track-changes.el: Improve error tracing to help debugging

track-changes.el: Improve error tracing to help debugging

Add a new `trace` setting for `track-changes-record-errors` to
record more information in order to try and help find the root
cause of errors.

* lisp/emacs-lisp/track-changes.el (track-changes--trace): New var.
(track-changes-record-errors): Document new `trace` setting.
(track-change--backtrace, track-changes--trace): New functions.
(track-changes--recover-from-error): Use them.
(track-changes--error-log): Document new format.
(track-changes-register, track-changes-unregister)
(track-changes-fetch, track-changes--before, track-changes--after):
Call `track-changes--trace`.

(cherry picked from commit ef587bf6b46b2ea3ef91b260ac2542666081260d)