MEDIUM: spoe: Remove fragmentation support

MEDIUM: spoe: Remove fragmentation support

It is the first patch of a long series to refactor the SPOE filter. The idea
is to rely on a dedicated multiplexer instead of hakcing HAProxy with a list
of applets processing a message queue.

First of all, optionnal features will be removed. Some will be restored at
the end, some others will just be removed. It is the case here. The frame
fragmentation support is removed. The only purpose of this feature is to be
able to support the streaming. Because it is out of the scope of this
refactoring, the fragmentation is removed.

The related issue is #2502.