Switch to openfast_io and update to OpenFAST v4.0.0

[mayankchetan]

Description and Purpose

This PR updates ROSCO to use the new openfast_io library for reading and writing OpenFAST files. Additionally, ROSCO is updated to track OpenFAST v4.0.0

Dependancies for PR:

• openfast_io: https://github.com/mayankchetan/openfast/tree/of_io_update (PR: updates to handle writing OpenFAST models from weis and wind_io OpenFAST/openfast#2603)

WEIS PR (WISDEM/WEIS#341) depends on this PR

Type of change

What types of change is it?
Select the appropriate type(s) that describe this PR

• Bugfix (non-breaking change which fixes an issue)
• New feature (non-breaking change which adds functionality)
• Breaking change (non-backwards-compatible fix or feature)
• Code style update (formatting, renaming)
• Refactoring (no functional changes, no API changes)
• Documentation update
• Maintenance update
• Other (please describe): Testing and examples

TODO Items General:

• Update examples & testing based on @dzalkind's recommendations
• ROSCO PR () & openfast_io PR () need to be merged

TODO Items API Change:

• Update docs with API change
• Run update_rosco_discons.py in Test_Cases/
• Update DISCON schema

Github issues addressed, if one exists

Examples/Testing, if applicable