Fix output_variables

[mattw-nws]

Fixes a crash when using "output_variables" key in Bmi_Multi_Formulation caused by failing static cast of templated classes. Switches the implementation to use DataProvider interface which requires simpler casts--and allows for inclusion of fields from forcing data as well.

Additions

Removals

Changes

• Fixed get_var_value_as_double(std::string) method

Testing

1. Automated test GetOutputLineForTimestep_3_a added, passes.

Screenshots

Notes

Todos

• Compution of time offsets is a little brute-forced... there may be a more elegant (or complete) way to do it, but this seems to function.

Checklist

• PR has an informative and human-readable title
• Changes are limited to a single goal (no scope creep)
• Code can be automatically merged (no conflicts)
• Code follows project standards (link if applicable)
• Passes all existing automated tests
• Any change in functionality is tested
• New functions are documented (with a description, list of inputs, and expected output)
• Placeholder code is flagged / future todos are captured in comments
• Project documentation has been updated (including the "Unreleased" section of the CHANGELOG)
• Reviewers requested with the Reviewers tool ➡️

Testing checklist (automated report can be put here)

1. See workflow runner output

Target Environment support

• Linux

[donaldwj]

Are the crashing test just the bad cython version?

[donaldwj]

I dont see any issues here, other than cython bug which is to be fixed elsewhere.

[mattw-nws]

Ha... Cython 0.29.29 was yanked. v0.29.30 passes.