cpp-common: template ArrayValueIterator for reuse with other containers

cpp-common: template ArrayValueIterator for reuse with other containers

This pattern will be reused for Structure and Variant field class.

Signed-off-by: Francis Deslauriers <francis.deslauriers@efficios.com>
Change-Id: I8b6521e41dcc2ebdb81b6348de916544176dbf20
Reviewed-on: https://review.lttng.org/c/babeltrace/+/7518
Reviewed-by: Philippe Proulx <eeppeliteloop@gmail.com>
Reviewed-on: https://review.lttng.org/c/babeltrace/+/10759
CI-Build: Philippe Proulx <eeppeliteloop@gmail.com>
Tested-by: jenkins <jenkins@lttng.org>