MB-16181: Reduce repetition in Manifest::Manifest throwing
MB-16181: Reduce repetition in Manifest::Manifest throwing

Lots of validation checks end up throwing std::invalid_argument
with the same "Manifest::Manifest" prefix. Reduce this repetition
to improve the readability of the function.

Change-Id: Ibbd9fe6f0f6ac5f6558212d43968988bd4ac268c
Reviewed-on: http://review.couchbase.org/c/kv_engine/+/134978
Reviewed-by: Trond Norbye <60edd2ef23891a753f231b0c6f161dc634079a93@couchbase.com>
Tested-by: Build Bot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>

daverigby/kv_engine,daverigby/kv_engine,daverigby/kv_engine,daverigby/kv_engine