WsStore should not report query misses as exceptions

WsStore currently returns soapfaults on fetch misses for any of the following issues:

1. Target Store name is invalid or not provided
2. Targeting non global entry but user not provided
3. Target key not provided
4. Unable to access root path on Dali (likely a configuration/load-time error)
5. Target namespace is invalid or not provided
6. Target key is invalid

I propose not throwing an exception for case 6 in order to cut down on log red herrings such as the sample below:

0000382C USR 2021-03-12 14:47:13.790 27459 10842 "Exception(s) in wsstore::Fetch - [ -1: DALI Keystore fetch: invalid key 'dp-mythor-samples::iris_sample_spark-wuid' detected!]

"