[WEB-5285] feat: enhance ChangeTrackerMixin to capture changed fields on save (#8270)

- Added an override for the save method in ChangeTrackerMixin to store changed fields before resetting tracking.
- Implemented a new method, _reset_tracked_fields, to ensure subsequent saves detect changes relative to the last saved state.
- Updated IssueComment to utilize _changes_on_save for determining changed fields, improving accuracy in tracking modifications.

apps/api/plane/db/models/issue.py

@@ -513,10 +513,12 @@ class IssueComment(ChangeTrackerMixin, ProjectBaseModel):
                     "comment_json": "description_json",
                 }
 
+                # Use _changes_on_save which is captured by ChangeTrackerMixin.save()
+                # before the tracked fields are reset
                 changed_fields = {
                     desc_field: getattr(self, comment_field)
                     for comment_field, desc_field in field_mapping.items()
-                    if self.has_changed(comment_field)
+                    if comment_field in self._changes_on_save
                 }
 
                 # Update description only if comment fields changed