Move aaa-app-config

The contract of this YANG is tied to a particular implementation, make
sure we are not part of the public API.

JIRA: AAA-205
Change-Id: I9d7edd389fcccd923a9ee5ded465d3f70b17ce70
Signed-off-by: Robert Varga <robert.varga@pantheon.tech>

diff --git a/aaa-shiro/api/src/main/yang/aaa-app-config.yang b/aaa-shiro/impl/src/main/yang/aaa-app-config.yang
similarity index 100%
rename from aaa-shiro/api/src/main/yang/aaa-app-config.yang
rename to aaa-shiro/impl/src/main/yang/aaa-app-config.yang