scripts/lib/abi/abi_parser.py: use an interactor for ReST output

scripts/lib/abi/abi_parser.py: use an interactor for ReST output

Instead of printing all results line per line, use an interactor
to return each variable as a separate message.

This won't change much when using it via command line, but it
will help Sphinx integration by providing an interactor that
could be used there to handle ABI symbol by symbol.

Signed-off-by: Mauro Carvalho Chehab <mchehab+huawei@kernel.org>
Signed-off-by: Jonathan Corbet <corbet@lwn.net>
Link: https://lore.kernel.org/r/e3c94b8cdfd5e955aa19a703921f364a89089634.1739182025.git.mchehab+huawei@kernel.org