HandlerMethodArgumentResolver is a non-blocking contract, however only
implementations that read the request body require blocking.
This commit introduces SyncMethodArgumentResolver as an extension of
the non-blocking contract that allows synchronous implementations to
use synchronous argument resolution.
There is also a SyncInvocableHandlerMethod extension that uses only
sync argument resolvers and allows a synchronous invocation.
Issue: SPR-14543
b55ab1119e