MB-30020 Test Subdoc-Validators set error context
MB-30020 Test Subdoc-Validators set error context

Test that the subdocument mcbp validators set the error context on
the request cookie upon validation failure.

Change-Id: Idf958e11bc0f6bba083c1aaa023624aedbee7bc5
Reviewed-on: http://review.couchbase.org/99084
Tested-by: Build Bot <80754af91bfb6d1073585b046fe0a474ce868509@couchbase.com>
Reviewed-by: Jim Walker <1cd02e31b43620d7c664e038ca42a060d61727b9@couchbase.com>

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