Commit fae8ca0c inadvertently removed the monitor at add/1 and
add_new/1. As a result, process death did not remove associations,
causing table diameter_reg to leak entries and stop/start of a service
to fail.

Add a testcase to detect the problem, which existing testcases miss.

* anders/diameter/sctp/OTP-10889:
  Make unordered delivery configurable

Changing the default in the parent commit is possibly a bit dangerous,
even if the motivation still holds. Take a step back and make unordered
delivery a matter of configuration, without changing the default:
configuration is {unordered, boolean() | pos_integer()}, with false the
default, and N equivalent to OS =< N, where OS is the number of outbound
streams negotiated on the association in question.

A user can mess with this by configuring an sctp_default_send_param of
their own, but unordered sending is them from start, not only after the
second message reception.

* anders/diameter/answer-message_decode/OTP-14596:
  Exercise answer-message/AVP decode in traffic suite
  Exercise answer-message/Failed-AVP decode in traffic suite

* anders/diameter/DOIC/OTP-14588:
  Exercise avp_dictionaries in traffic suite
  Let generic AVPs be encoded/decoded in alternate dictionaries
  Rename field in codec map: dictionary -> app_dictionary
  Add RFC 7683 Diameter Overload Indicator Conveyance text and dictionary
  Fix decode undef
  Fix dictionary compilation error message

In particular, that arbitrary application AVPs are decoded in an answer
setting the E-bit.

In particular, that application AVPs in Failed-AVP are decoded in an
answer setting the E-bit.

As introduced in the parent commit.

To better reflect what the field is: field 'module' is the dictionary
module that's calling diameter_gen to decode a list of AVP, while field
'app_dictionary' is the dictionary module defining the message being
decoded.

Which motivates the avp_dictionaries config that will be added in
a subsequent commit.