Fix the few most pressing warnings reported by -Wall

[PhilMiller]

Changes

• Fix occurrences of -Wpessimizing-move reported by either GCC or AppleClang
• Fix a mis-use of bitwise | instead of logical ||
• Fix range-for loop over vector<string> working on values rather than references
• Quiet some -Wmaybe-uninitialized by setting output-argument pointer variables to nullptr
• Fix catching polymorphic boost::bad_get by value

Testing

1. Local testing with GCC 13
2. Local testing with AppleClang 15
3. CI with GCC 11
4. CI with AppleClang 14

Notes

This gets us a large portion of the way to being able to build with -Wall for C++

• There are a lot of un/signed comparison warnings that I think we can reasonably suppress (-Wsign-compare)
• There are some constructor initializer list warnings about orders not matching declarations, that we should probably just fix, but aren't a big deal
• There are a bunch of unused variables and functions that should eventually be investigated and likely deleted
• The BMI C++ spec misses a virtual destructor, so we get warnings about that until https://github.com/csdms/bmi-cxx/issues/11 gets addressed, and we incorporate the fix in our modules (-Wnon-virtual-dtor)

Checklist

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

[PhilMiller]

If we merge this, then the actual ngen code and its tests compiles with -Werror -Wall -Wno-reorder -Wno-unused -Wno-sign-compare on GCC 13. The others are less definitively problematic.

[PhilMiller]

The selection of flags added to CI is based on which ones are available for both GCC and AppleClang. Otherwise, the build just fails with unrecognized command line arguments.