Add test_wc_WolfEventDecisionCoverage (group "wolfevent") driving the
wolfEvent / wolfEventQueue_* doubly-linked FIFO from the public API:
the queue==NULL || event==NULL guards (Push/Pop/Add/Remove, each operand
plus the all-false half), the Add first-element branch, the Remove
head/tail/sole cascade including the (event==head && event==tail) AND and
the defensive (next==NULL || prev==NULL) corruption guard, and the Poll
context-filter OR.
Guarded by HAVE_WOLF_EVENT (compiled empty otherwise). The queue core is
async-independent; it builds standalone (no WOLFSSL_ASYNC_CRYPT) now that
BUILD_WOLFEVENT is true under --enable-usersettings and wolfEvent_Poll no
longer warns on unused params in non-async builds.