Support for HDF5?

### Question about importer

Hello ML.NET Team,

It's so amazing to see that we .NET People really got a spark or scikit like Framework! From what I saw we can be proud of. 👍

Now the question

**Did you consider to write HDF5 importer?**

Maybe I should explain. HDF5 is a very flexible and great data Format which is often used in Simulation area - the MATLAB file Format *.mat bases on HDF5. There exist many Python and Java Projects for HDF5 if you look at Github and on their web page https://portal.hdfgroup.org/display/support. But I really missing us .NET developers in this area. We have C#, F# and Powershell (also have VB.NET) and I find it would be good for .NET and the HDF5 if we work together. ;)

Maybe a 2nd hint to Microsoft and ML.NET Team - there exist also the Project HDFql for SQL like query for my data - Image like "give me all Arrays with have a tag "Temperatur" or "give me all data with unit "°C". ^^

Inizia esaminando la richiesta dell'issue relativa a un importer HDF5 e la pagina di supporto di HDF Group collegata, quindi determina se ML.NET dispone già di un punto di ingresso per l'importer che possa accoglierla. L'issue non identifica file, test, ambito HDF5 supportato o criteri di accettazione, quindi il lavoro non è definito abbastanza da stabilire come riconoscere che è completato.

Scritto dal modello di indicizzazione a partire dal testo della issue.