Squashed 'lib/vendor/wp-bootstrap-navwalker/' content from commit dee2a32

git-subtree-dir: lib/vendor/wp-bootstrap-navwalker
git-subtree-split: dee2a32adaeededc7ce58b2c2fd0bbc782d5e5b2
Merge commit '9038df03146445a0ae282f4537abd5f3e801590e' as 'lib/vendor/wp-bootstrap-navwalker'
integrate navwalker