.Net: Allow instances of ISKFunction to be used with different Kernel instances

[markwallace-microsoft]

Important

Labeled Urgent because it will require a breaking change.

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1. Create ADR for ISKFunction to be used with different Kernel

[markwallace-microsoft]

The code to register a function with a Kernel is implemented as follows

    public ISKFunction RegisterCustomFunction(ISKFunction customFunction)
    {
        Verify.NotNull(customFunction);

        customFunction.SetDefaultFunctionCollection(this.Functions);
        this._functionCollection.AddFunction(customFunction);

        return customFunction;
    }

The call to customFunction.SetDefaultFunctionCollection(this.Functions) causes the ISKFunction instance to be linked to the current Kernel instance. This means it cannot be reused.

The means we cannot reuse an ISKFunction instance and we have to recreate these. This can be an expensive operation e.g. for semantic functions which rely on a prompt template which will need to be parsed multiple times.

[matthewbolanos]

@alliscode, we'll likely need your help to know if this is a problem needing solving for v1.0.0

[markwallace-microsoft]

This is resolved and the current methods that link a semantic function to a kernel instance are now obsolete