ToImmutableDictionary extension methods do not document throwing exceptions on key collisions

[juliusl]

The current documentation for ToImmutableDictionary does not document that it throws on a key collision.

https://learn.microsoft.com/en-us/dotnet/api/system.collections.immutable.immutabledictionary.toimmutabledictionary?view=net-9.0

When converting a collection from a to b, the intuitive behavior would be to either skip the value or offer a method overload that gives the user an escape hatch. Since, it doesn't appear an escape hatch exists from the current api, I think at minimum this should be documented on the extension methods.

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[huoyaoyuan]

For reference, LINQ Enumerable.ToDictionary documents the exception.

Bonus note: ImmutableDictionary is probably not what people want and it's not performant. Check FrozenDictionary.