Redefine AbstractMessageParser object parsing

Redefine AbstractMessageParser object parsing

All AbstractMessageParser.validate() interact with the list of objects
by peeking at the first element and removing it when handled. While
the List contract supports it, there is no efficient implementation:
LinkedList is wasteful with memory (and its locality), ArrayList ends
up shifting arrays all the time.

Deal with this dilemma by recognizing we are dealing with a Queue, and
realize it through ArrayDeque. Let users deal with the logic rewrite,
which ends up being rather sensible: they are always looking only at the
first element anyway.

This also exposes a few places where we can run into runtime exceptions
-- mark those with FIXMEs for future improvement.

JIRA: BGPCEP-976
Change-Id: I882c7208dddd61f368499fd661e6d090752d144d
Signed-off-by: Robert Varga <robert.varga@pantheon.tech>