Enrich the AvaloniaDictionary constructor

[IoannTerrible]

Currently, the AvaloniaDictionary class only provides two constructors, which limits the flexibility when initializing it with an existing dictionary. Often, developers have a ready-made Dictionary<TKey, TValue> that they wish to convert into an AvaloniaDictionary, but they lack a straightforward constructor for this purpose.

I propose adding a new constructor to the AvaloniaDictionary class that accepts an existing Dictionary<TKey, TValue>. This would simplify the process of converting an existing dictionary to an AvaloniaDictionary. The constructor would look like this:

    public AvaloniaDictionary(Dictionary<TKey, TValue> initialDictionary)
    {

        _inner = new Dictionary<TKey, TValue>(initialDictionary);
    }