cli: introduce BT_CLI_LOG*_APPEND_CAUSE() and use it where appropriate

cli: introduce BT_CLI_LOG*_APPEND_CAUSE() and use it where appropriate

BT_CLI_LOGE_APPEND_CAUSE() and BT_CLI_LOGW_APPEND_CAUSE() are internal
CLI macros which log and append an error cause with the same message,
using "Babeltrace CLI" as the cause's module name.

Signed-off-by: Philippe Proulx <eeppeliteloop@gmail.com>
Change-Id: I2202ce81582860247232cd3aeea82aa3561e1227
Reviewed-on: https://review.lttng.org/c/babeltrace/+/1616
Tested-by: jenkins <jenkins@lttng.org>
Reviewed-by: Francis Deslauriers <francis.deslauriers@efficios.com>