[bp/c11a1e80] [FIX] trackers: Add a new optional param to `\TrackerLib::field_render_value`...

[FIX] trackers: Add a new optional param to \TrackerLib::field_render_value to prevent it assigning the field value to smarty and use this in \TrackerLib::get_all_items, where the value changes for each item. This fixes a weird edge case in wikiplugin_tracker when an ItemLink field uses one of the fields in the tracker form in it's display fields, which was making the form input be rendered as an output (due to this global smarty assignment). Thanks @guill for the research and identifying the culprit!