Improve NetworkAdminService Code Coverage

[povolev15]

Add more unit tests to improve code coverage to each class in Network Admin 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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CODEC

• [ ] MonoSpecialFilesAdapterCodec [85 %]

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HANDLERS

• [ ] FreezeHandler [93%]
• [x] FreezeUpgradeActions [100 %]
• [x] #13196
• [ ] NetworkGetAccountDetailsHandler [93 %]
• [x] NetworkGetByKeyHandler [100 %]
• [x] NetworkGetExecutionTimeHandler [100 %]
• [ ] NetworkGetVersionInfoHandler [92 %]
• [x] NetworkTransactionGetFastRecordHandler [100 %]
• [ ] NetworkTransactionGetReceiptHandler [93 %]
• [ ] NetworkTransactionGetRecordHandler [64%]
• [ ] NetworkUncheckedSubmitHandler [75%]
• [ ] ReadableFreezeUpgradeActions [58%]
• [ ] UnzipUtility [78%]

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SCHEMAS

• [ ] InitialModServiceAdminSchema[77 %]
• [ ] InitialModServiceNetworkSchema [0%]

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SERDES

• [ ] EntityNumCodec [85 %]
• [ ] MonoContextAdapterCodec [83%]
• [ ] MonoRunningHashesAdapterCodec [85%]

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UTILS

• [ ] NetworkAdminServiceUtil [66 %]

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BASE PACKAGE

• [x] FreezeServiceImpl [100%]
• [ ] NetworkServiceImpl [0 %]
• [ ] ReadableFreezeStoreImpl [62 %]
• [x] WritableFreezeStore [100 %]