Refactor ImmutableMapEntryNodeSchemaAwareBuilder
This builder's logic is not entirely efficient, as it can constructs
unnecessary NodeIdentifierWithPredicates purely for checking purposes.
Furthermore we can side-step child validation when we are switching
by available children, as we have the entryset available.
JIRA: YANGTOOLS-917
Change-Id: I57d0a156ced3abce7e61403c2b390c074850d612
Signed-off-by: Robert Varga <robert.varga@pantheon.tech>
(cherry picked from commit
c43197e66be08a0ffaa00bbe8405fa4ba23b8656)