Fix augmented action code generation

Fix augmented action code generation

When an action is introduced as part of an augment statement, we
attempt to generate it in the augmented module, which refuses to
generate its input/output statements, leading to a NPE.

This patch updates codegen to ignore augmenting actions in the
augmented module and process them as part of augmentation.

JIRA: MDSAL-459
Change-Id: Ibd7d7abc5ec1eec6d32ee1885da00a0de69b2445
Signed-off-by: Robert Varga <robert.varga@pantheon.tech>
(cherry picked from commit dee452d009946a175273ac2a21dca4174b2142af)