lisa.analysis.load_tracking: Add optional `update_time` column in df_tasks_signal()
lisa.analysis.load_tracking: Add optional `update_time` column in df_tasks_signal()

If the column is available, add it to the output dataframe.

credp/lisa,credp/lisa,ARM-software/lisa,ARM-software/lisa,credp/lisa,ARM-software/lisa,credp/lisa,ARM-software/lisa