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-milestone.svg

@@ -1 +1 @@
-<svg viewBox="0 0 16 16" class="svg octicon-milestone" width="16" height="16" aria-hidden="true"><path fill-rule="evenodd" d="M7.75 0a.75.75 0 01.75.75V3h3.634c.414 0 .814.147 1.13.414l2.07 1.75a1.75 1.75 0 010 2.672l-2.07 1.75a1.75 1.75 0 01-1.13.414H8.5v5.25a.75.75 0 11-1.5 0V10H2.75A1.75 1.75 0 011 8.25v-3.5C1 3.784 1.784 3 2.75 3H7V.75A.75.75 0 017.75 0zm0 8.5h4.384a.25.25 0 00.161-.06l2.07-1.75a.25.25 0 000-.38l-2.07-1.75a.25.25 0 00-.161-.06H2.75a.25.25 0 00-.25.25v3.5c0 .138.112.25.25.25h5z"/></svg>
+<svg viewBox="0 0 16 16" class="svg octicon-milestone" width="16" height="16" aria-hidden="true"><path fill-rule="evenodd" d="M7.75 0a.75.75 0 0 1 .75.75V3h3.634c.414 0 .814.147 1.13.414l2.07 1.75a1.75 1.75 0 0 1 0 2.672l-2.07 1.75a1.75 1.75 0 0 1-1.13.414H8.5v5.25a.75.75 0 1 1-1.5 0V10H2.75A1.75 1.75 0 0 1 1 8.25v-3.5C1 3.784 1.784 3 2.75 3H7V.75A.75.75 0 0 1 7.75 0zm0 8.5h4.384a.25.25 0 0 0 .161-.06l2.07-1.75a.25.25 0 0 0 0-.38l-2.07-1.75a.25.25 0 0 0-.161-.06H2.75a.25.25 0 0 0-.25.25v3.5c0 .138.112.25.25.25h5z"/></svg>