Fix item with the same key exception

[HebaruSan]

Problem

The Artemis II KSP revival continues to summon new and interesting problems to the Discord:

System.ArgumentException: An item with the same key has already been added.
   at System.ThrowHelper.ThrowArgumentException(ExceptionResource resource)
   at System.Collections.Generic.Dictionary`2.Insert(TKey key, TValue value, Boolean add)
   at System.Collections.Generic.Dictionary`2..ctor(IDictionary`2 dictionary, IEqualityComparer`1 comparer)
   at CKAN.Registry.DeSerialisationFixes(StreamingContext context)

Reported by Discord user JLSkyzer.

Cause

The user had installed both KOSHUD and kOS-Computer on Windows using a version of CKAN older than #3479, so their registry.json's installed_files object contained both of these:

"Ships/Script/Boot": "KOSHUD",
"Ships/Script/boot": "kOS-Computer",

These represent the same folder on Windows, so when we load that registry, newer versions of CKAN use Platform.PathComparer to coalesce them into one entry. Unfortunately that causes an exception to be thrown.

Changes

Now we filter out duplicate keys before we make the dictionary.

[coveralls]

Coverage Report for CI Build 24478773103

Coverage remained the same at 85.549%

Details

• Coverage remained the same as the base build.
• Patch coverage: 1 of 1 lines across 1 file are fully covered (100%).
• No coverage regressions found.

Uncovered Changes

No uncovered changes found.

Coverage Regressions

No coverage regressions found.

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Coverage Stats

Relevant Lines:	14229
Covered Lines:	12019
Line Coverage:	84.47%
Relevant Branches:	2164
Covered Branches:	2005
Branch Coverage:	92.65%
Branches in Coverage %:	Yes
Coverage Strength:	1.76 hits per line

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💛 - Coveralls