Add searchEngineOrBot request flag in page cache key

As of HSTTWO-4627, asynchronous components are disabled automatically on search engine or bot requests.
But at the moment, it doesn't seem to differentiate normal requests from those in terms of page cache key generation.
So, if a search engine makes a request on a page, resulting the page cache item being generated, then the normal requests afterward would get cached page without asynchronous handling pages such as component rendering urls for next ajax calls.

Therefore, it would make sense to add the boolean flag in the page cache key, too.