Registry: add basic ISO_C_BINDING types

[andrew-platt]

Might be ready to merge, if it doesn't need a complete rewrite.

Feature or improvement description
I needed a way to generate some simple registry files containing a limited number of types from the ISO_C_BINDING intrinisic library. This ugly mess of code (I have no idea how to code in C/C++) seems to work, but is likely terribly ugly and missing some important things.

To use this feature, add ISO_C_BINDING by itself on a line someplace in the registry text file

Related issue, if one exists
N/A

Impacted areas of the software
Registry only. May provide value for generating registries for c-binding libraries (many of those have a messy interface with a mix of c and fortran types arranged in ugly messes of derived types).

This should not change any existing _Types.f90 contents when regenerated.

Test results, if applicable
No results affected.

[Copilot]

Pull Request Overview

This PR adds support for basic ISO_C_BINDING types to the OpenFAST registry code generator. The feature allows registry files to include C-compatible data types by adding ISO_C_BINDING as a directive.

• Adds parsing for ISO_C_BINDING directive in registry files
• Implements basic C-compatible data types (c_int, c_float, c_double, c_char)
• Generates appropriate USE statements in output Fortran modules

Reviewed Changes

Copilot reviewed 3 out of 3 changed files in this pull request and generated 3 comments.

File	Description
registry_parse.cpp	Adds parsing logic to detect ISO_C_BINDING directive and set flag
registry_gen_fortran.cpp	Generates USE ISO_C_BINDING statement when flag is set
registry.hpp	Adds data structures and logic for C-binding data types

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[deslaughter]

This is a really good addition