Fixed DirectQuerySupportImpl small cluster String value retrieval

Previous too-optimized implementation had multiple flaws:
* Index calculation did not have enough parenthesis in it which meant
  that the value table index was sometimes calculated incorrectly.
  This lead to string literal values being read incorrectly.
* Did not take into account string literals longer than 127 characters
* Did not take into account that string literals are modified-utf-8
  encoded and simply decoded them as US-ASCII bytes. Essentially all
  resources with name containing special characters were indexed
  incorrectly up until now.

All of these flaws have been in the code for ages.

gitlab #86

Change-Id: I500114d3e2cff76370433b929ec8b8124659ce33