Support loading data from JsonValue for JsonProvider.

[voroninp]

JsonProvider supports loading data from uri, stream, and stream reader, but not JsonValue which is inconvenient.

Now I had to use it like this:

use ms = new MemoryStream()
use w = new StreamWriter(ms, leaveOpen=false)
value.WriteTo(w, JsonSaveOptions.DisableFormatting)
w.Flush()
ms.Seek(0L, SeekOrigin.Begin) |> ignore
let record = DayCloseData.Load(ms)

Instead of just let record = = DayCloseData.Load(value)

---

If you a curious why I need this, I can explain.

Some services return such payload:

{
    "history": {
        "2020-01-10": {
            ...
        },
        "2020-01-11": {
            ...
        }
    }
}

[mlaily]

I agree that some json cannot be statically parsed and that it would be useful to be able to create an instance from a JsonValue, but note that your workaround can be simplified to value.ToString() |> DayCloseData.Parse.