the configuration write guard is now required when the configuration
struct shall be mutated. the write guards locks multiple writers against
each other and also, more importantly, makes the writes synchronous to
the main loop. all code running in the main loop can now be sure that
(1) reads from the configuration struct are non-preemtive and (2) the
configuration struct as a whole is in a consistent state when reading
from it.
NOTE that acquiring a write guard from within the main loop's task will
immediately cause a deadlock and the watchdog will trigger a reset. if
writing from inside the main loop should ever become necessary, the
write guard must be updated to only lock the mutex but not wait for a
signal.
with ESPAsyncWebServer 3.3.0, the setAuthentication() method became
deprecated and a replacement method was provided which acts as a shim
and uses the new middleware-based approach to setup authentication. in
order to eventually apply a changed "read-only access allowed" setting,
the setAuthentication() method was called periodically. the shim
implementation each time allocates a new AuthenticationMiddleware and
adds it to the chain of middlewares, eventually exhausting the memory.
we now use the new middleware-based approach ourselves and only add the
respective AuthenticatonMiddleware instance once to the respective
websocket server instance.
a regression where enabling unauthenticated read-only access is not
applied until reboot is also fixed. all the AuthenticationMiddleware
instances were never removed from the chain of middlewares when calling
setAuthentication("", "").
