Update both BMI C++ header copies to reflect virtual destructor

[PhilMiller]

Addresses the model engine element of #831.

These PRs need to be merged in tandem:

• Update both BMI C++ header copies to reflect virtual destructor #832
• Update bmi.hxx to reflect addition of virtual destructor SLoTH#7
• Update BMI C++ header to match upstream with virtual dtor SoilMoistureProfiles#17
• Update BMI C++ header to match upstream with virtual dtor SoilFreezeThaw#25
• Update BMI C++ header to match upstream with virtual dtor and correct namespace LGAR-C#26

Changes

• Modify the declaration to virtual ~Bmi()
• Update the submodule copy of the reference bmi-cxx/bmi.hxx to match upstream

Testing

1. Local CI
2. CI of SloTH, SMP, SFT, and LGAR-C, modified to cross-reference each others' updates

Notes

• All of the supported modules are going to have to make the switch in a somewhat coordinated fashion. This PR should perhaps encompass updating the submodule versions of any such that are affected, to make an atomic step forward.

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 ➡️

[hellkite500]

Routing test failure is unrelated and will be addressed separately.