using virtual fuction instead of reflection

[SimaTian]

###Part of #11160
Building on top of Eric's IPC pr - his work allowed for other bottlenecks to reveal themselves.

Context

Currently, the ReadFromStream function uses

ArgsReaderDelegate readerMethod = (ArgsReaderDelegate)CreateDelegateRobust(typeof(ArgsReaderDelegate), _buildEvent, methodInfo);

for a large portion of it's packet deserialization. This is large enough to be seen in the performance profiler as shown above more than 3% of CPU an it's on a critical path.
When I checked, the function was already virtual so the change is minimal. Unfortunately I had to make an allowance to the task host since it wasn't compatible.

Changes Made

Exposed a convenience public endpoint for the CreateFromStream function, that calls the virtual method Create from stream.
Used this endpoint instead of delegate creation.

Testing

As long as nothing breaks, I consider that a win.
I did local profiling.