Treat warnings as errors on release mode

[jslee02]

• Treat warnings as errors on release mode by default
• Remove DART_TREAT_WARNINGS_AS_ERRORS option
• Fix compile warnings with GCC 11.2

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Before creating a pull request

• Document new methods and classes
• Format new code files using clang-format

Before merging a pull request

• Set version target by selecting a milestone on the right side
• Summarize this change in CHANGELOG.md
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[codecov]

Codecov Report

Merging #1629 (ce2d84e) into main (3e0edda) will not change coverage.
The diff coverage is n/a.

@@           Coverage Diff           @@
##             main    #1629   +/-   ##
=======================================
  Coverage   58.92%   58.92%           
=======================================
  Files         477      477           
  Lines       40192    40192           
=======================================
  Hits        23685    23685           
  Misses      16507    16507           

Impacted Files	Coverage Δ
dart/collision/dart/DARTCollide.cpp	45.53% <ø> (ø)
python/dartpy/eigen_geometry_pybind.cpp	41.76% <ø> (ø)

[traversaro]

Just FYI, probably the "Treat warnings as errors on release mode" will need to be patched out in the version used in package managers of DART, as it is quite common that an older version of DART needs to be compiled with newer compilers, and this creates new warnings, that if use of -Werror is forced result in errors.

See also slide 43 of https://raw.githubusercontent.com/CppCon/CppCon2018/master/Presentations/dont_package_your_libraries_write_packagable_libraries/dont_package_your_libraries_write_packagable_libraries__robert_schumacher__cppcon_2018.pdf .

[jslee02]

@traversaro This makes sense to me. The motivation of this change was to prevent the case that the contributor and the CI don't fix the warnings by forgetting turnning on DART_TREAT_WARNINGS_AS_ERRORS option at least on release mode build. I think this option would be still useful as it gives options to the pacakge managers. Let me revive the option and make sure the CI to turn on the options instead. Thanks for the feedback!