Add support for .NET and Python SnapStart #1627

Today AWS launched SnapStart for Python and .NET Lambda functions.

At the moment the Java SnapStart functions seem broken. There are fixes mentioned in #808.

If they were resolved it would be good to have .NET and Python SnapStart timings. Looking at #1626 I can kind of see what would be required to add new lambda functions (for .NET at least), but I don't think I have the ability to test what was mentioned in #808 to ensure the tests are running correctly.

I don't think I could do the Python related tasks.