FPGA read/write APIs.

[amehra-ni]

What does this Pull Request accomplish?

This PR contains code generation for Read/Write FPGA functions.

Why should this Pull Request be merged?

• Update config.py files so the new data type can map correctly.
• Added a few more narrow types in KNOWN_COERCED_NARROW_NUMERIC_TYPES.

What testing has been done?

• No compile or codegen issues.
• Manually verified server handlers for all APIs and compared them with documentation for the APIs mentioned.
• Manually tested Read/Write(normal), Read/Write(array), Read(Fifo) with client code which calls the functions correctly and data is as expected. In the process of testing Write(Fifo).