Create fasta from hvcf fix duplicate entries

[lynnjo]

Description

When creating a haplotype fasta from an hvcf file, there should not be duplicates. Fixed the code so that resulting fasta files will contain no more than 1 instance of a haplotype with its sequence.

Type of change

What type of changes does your code introduce? Put an x in boxes that apply.

• [ ] CHANGE (fix or feature that would cause existing functionality to not work as expected)
• [ ] FEATURE (non-breaking change which adds functionality)
• [x] BUGFIX (non-breaking change which fixes an issue)
• [ ] ENHANCEMENT (non-breaking change which improves existing functionality)
• [ ] NONE (if none of the other choices apply. Example, tooling, build system, CI, docs, etc.)

Checklist:

• [x] I have performed a self-review of my code
• [x] I have commented my code, particularly in hard-to-understand areas
• [ ] I have updated relevant documentation

Changelog entry

Please add a one-line changelog entry below. This will be copied to the changelog file during the release process.

CreateFastaFromHvcf now correctly contains a single instance of a haplotype sequence when when creating haplotype fastas.

[codecov[bot]]

Codecov Report

All modified and coverable lines are covered by tests :white_check_mark:

Project coverage is 82.80%. Comparing base (89c340f) to head (56aa333). Report is 7 commits behind head on main.

Additional details and impacted files

```diff @@ Coverage Diff @@ ## main #212 +/- ## ======================================= Coverage 82.80% 82.80% ======================================= Files 77 77 Lines 5054 5054 Branches 837 837 ======================================= Hits 4185 4185 Misses 557 557 Partials 312 312 ```

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