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-trash.svg

@@ -0,0 +1 @@
+<svg viewBox="0 0 16 16" class="svg octicon-trash" width="16" height="16" aria-hidden="true"><path fill-rule="evenodd" d="M6.5 1.75a.25.25 0 0 1 .25-.25h2.5a.25.25 0 0 1 .25.25V3h-3V1.75zm4.5 0V3h2.25a.75.75 0 0 1 0 1.5H2.75a.75.75 0 0 1 0-1.5H5V1.75C5 .784 5.784 0 6.75 0h2.5C10.216 0 11 .784 11 1.75zM4.496 6.675a.75.75 0 1 0-1.492.15l.66 6.6A1.75 1.75 0 0 0 5.405 15h5.19c.9 0 1.652-.681 1.741-1.576l.66-6.6a.75.75 0 0 0-1.492-.149l-.66 6.6a.25.25 0 0 1-.249.225h-5.19a.25.25 0 0 1-.249-.225l-.66-6.6z"/></svg>