Add missing author extension for items with Population Context Extension

[barhodes]

When populating an item with the SDC Questionnaire Item Population Context extension no QuestionnaireResponse Author extension was being added denoting that the item had been answered by CQL Evaluation.

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Codecov Report

Attention: Patch coverage is 92.85714% with 1 lines in your changes are missing coverage. Please review.

Project coverage is 53.32%. Comparing base (baa2cda) to head (232ebad).

Files	Patch %	Lines
...questionnaire/populate/ProcessItemWithContext.java	83.33%	0 Missing and 1 partial :warning:

Additional details and impacted files

```diff @@ Coverage Diff @@ ## master #436 +/- ## ============================================ + Coverage 53.29% 53.32% +0.02% - Complexity 2133 2134 +1 ============================================ Files 281 281 Lines 11837 11843 +6 Branches 1618 1619 +1 ============================================ + Hits 6309 6315 +6 + Misses 4913 4912 -1 - Partials 615 616 +1 ```

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