Since #38616 there's exception type variance in getSession() between RequestStack and Request, when the session is not found

vs.

for simplicity, i think we should throw the same exception type in Request::getSession(), and let RequestStack simply forward the call.

the catch(BadMethodCallException) as "cheap hasSession" will break, but we explicitly mentioned to use hasSession instead already

ppl doing it as of 5.x rely on implementation details (the @throws BadMethodCallException isnt documented)

so, given both are LogicException it seems reasonable :)

cc @jderusse