destruction_helpers.h: remove using namespace KDBindings

[lemirep]

Because headers should never have a using namespace declaration.

Also fix typos, add unit tests and minimal documentation.

Change-Id: Ic524c53417da7273c15c1c9eaa5f8ef8758340af

[iamsergio]

was going to suggest we don't care about cppcheck for tests, but these are new errors, can you check which make sense and blacklist checks that are nonsense

[lemirep]

Fixed clang-tidy and cpp-check warnings