Update JS dependencies (#15033)

* Update JS dependencies

- Update all JS dependencies
- For octicons, rename trashcan to trash
- For svgo, migrate to v2 api, output seems to have slightly changed but icons look the same
- For stylelint, update config, fix custom property duplicates
- For monaco, drop legacy Edge support
- For eslint, enable new rules, fix new issues
- For less-loader, remove deprecated import syntax

* update svgo usage in generate-images and rebuild logo.svg with it

public/img/svg/octicon-fold-up.svg

@@ -1 +1 @@
-<svg viewBox="0 0 16 16" class="svg octicon-fold-up" width="16" height="16" aria-hidden="true"><path fill-rule="evenodd" d="M7.823 1.677L4.927 4.573A.25.25 0 005.104 5H7.25v3.236a.75.75 0 101.5 0V5h2.146a.25.25 0 00.177-.427L8.177 1.677a.25.25 0 00-.354 0zM13.75 11a.75.75 0 000 1.5h.5a.75.75 0 000-1.5h-.5zm-3.75.75a.75.75 0 01.75-.75h.5a.75.75 0 010 1.5h-.5a.75.75 0 01-.75-.75zM7.75 11a.75.75 0 000 1.5h.5a.75.75 0 000-1.5h-.5zM4 11.75a.75.75 0 01.75-.75h.5a.75.75 0 010 1.5h-.5a.75.75 0 01-.75-.75zM1.75 11a.75.75 0 000 1.5h.5a.75.75 0 000-1.5h-.5z"/></svg>
+<svg viewBox="0 0 16 16" class="svg octicon-fold-up" width="16" height="16" aria-hidden="true"><path d="M7.823 1.677 4.927 4.573A.25.25 0 0 0 5.104 5H7.25v3.236a.75.75 0 1 0 1.5 0V5h2.146a.25.25 0 0 0 .177-.427L8.177 1.677a.25.25 0 0 0-.354 0zM13.75 11a.75.75 0 0 0 0 1.5h.5a.75.75 0 0 0 0-1.5h-.5zm-3.75.75a.75.75 0 0 1 .75-.75h.5a.75.75 0 0 1 0 1.5h-.5a.75.75 0 0 1-.75-.75zM7.75 11a.75.75 0 0 0 0 1.5h.5a.75.75 0 0 0 0-1.5h-.5zM4 11.75a.75.75 0 0 1 .75-.75h.5a.75.75 0 0 1 0 1.5h-.5a.75.75 0 0 1-.75-.75zM1.75 11a.75.75 0 0 0 0 1.5h.5a.75.75 0 0 0 0-1.5h-.5z"/></svg>