The GraphQL language negotiation method is unusable with caching turned on

Currently the operation events are being fired only when retrieving executing an uncached operation. When retriving a cache entry in a multilingual setup it will contain a cache context for the content language. If the operation events are not fired then we cannot set the language in the execution context and therefore the language negotiation method will not be able to return anything. In order to solve the issue the operation events have to be called always before and after an operation even if reading from a cache entry.