Improve FileService Code Coverage

[povolev15]

Add more unit tests to improve code coverage to each class in File Service

1. Checked box without issue indicates False negative for coverage where codacy reports 0% coverage but test exists.
2. Checked box with Issue indicates the associated issue has been addressed.
3. List items in bold represent classes falling below 80% coverage and targeted for improvement

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base

• [x] FileQueryBase [100%]

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CODEC

• [x] FileServiceStateTranslator [100 %]

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HANDLERS

• [ ] #13188
• [ ] FileCreateHandler [88 %]
• [ ] #13189
• [ ] FileGetContentsHandler [81 %]
• [ ] FileGetInfoHandler [87 %]
• [ ] #13190
• [ ] #13191
• [ ] #13192
• [ ] #13193
• [ ] FileUpdateHandler [83%]

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SCHEMAS

• [ ] InitialModFileGenesisSchema[84 %]

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UTIL

• [ ] FileServiceUtils [93 %]

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BASE PACKAGE

• [ ] #13194
• [x] FileStore [100 %]
• [x] ReadableFileStoreImpl [100 %]
• [ ] ReadableUpgradeFileStoreImpl [90 %]
• [ ] WritableFileStore [87 %]
• [ ] WritableUpgradeFileStore [100 %]