Refactor ContainerEffectiveStatementImpl
The story here is very similar to ListEffectiveStatementImpl,
with the additional simplifications that containers are pretty
much same.
Size reduction from this refactor ends up being typical 104 bytes
to 40 bytes typical, eliminating a bunch of static collections
in the process.
JIRA: YANGTOOLS-1065
Change-Id: I1050c4e8f82f60274c78e810fc31896daccba389
Signed-off-by: Robert Varga <robert.varga@pantheon.tech>
(cherry picked from commit
bbdfd546e8f79773f2162717f607551bb79fcbda)