Update JS dependencies and webpack (#14118)

* Update JS dependencies

- Update all JS dependencies
- Adapt webpack config for version 5
- Update to Less 4.0, adapting usage of removed mixin syntax
- Enable new ESLint rules and fix discovered issues

* update license-webpack-plugin to fix missing licenses

* update license-webpack-plugin once more to get webpack into the license output

* switch to license-checker-webpack-plugin again for performance

* update deps again

Co-authored-by: Lauris BH <lauris@nix.lv>

public/img/svg/octicon-dash.svg

@@ -1 +1 @@
-<svg viewBox="0 0 16 16" class="svg octicon-dash" width="16" height="16" aria-hidden="true"><path fill-rule="evenodd" d="M2 8a.75.75 0 01.75-.75h10.5a.75.75 0 010 1.5H2.75A.75.75 0 012 8z"/></svg>
+<svg viewBox="0 0 16 16" class="svg octicon-dash" width="16" height="16" aria-hidden="true"><path fill-rule="evenodd" d="M2 7.75A.75.75 0 012.75 7h10a.75.75 0 010 1.5h-10A.75.75 0 012 7.75z"/></svg>

public/img/svg/octicon-plus.svg

@@ -1 +1 @@
-<svg viewBox="0 0 16 16" class="svg octicon-plus" width="16" height="16" aria-hidden="true"><path fill-rule="evenodd" d="M8 2a.75.75 0 01.75.75v4.5h4.5a.75.75 0 010 1.5h-4.5v4.5a.75.75 0 01-1.5 0v-4.5h-4.5a.75.75 0 010-1.5h4.5v-4.5A.75.75 0 018 2z"/></svg>
+<svg viewBox="0 0 16 16" class="svg octicon-plus" width="16" height="16" aria-hidden="true"><path fill-rule="evenodd" d="M7.75 2a.75.75 0 01.75.75V7h4.25a.75.75 0 110 1.5H8.5v4.25a.75.75 0 11-1.5 0V8.5H2.75a.75.75 0 010-1.5H7V2.75A.75.75 0 017.75 2z"/></svg>

public/img/svg/octicon-strikethrough.svg

@@ -0,0 +1 @@
+<svg viewBox="0 0 16 16" class="svg octicon-strikethrough" width="16" height="16" aria-hidden="true"><path fill-rule="evenodd" d="M7.581 3.25c-2.036 0-2.778 1.082-2.778 1.786 0 .055.002.107.006.157a.75.75 0 01-1.496.114 3.56 3.56 0 01-.01-.271c0-1.832 1.75-3.286 4.278-3.286 1.418 0 2.721.58 3.514 1.093a.75.75 0 11-.814 1.26c-.64-.414-1.662-.853-2.7-.853zm3.474 5.25h3.195a.75.75 0 000-1.5H1.75a.75.75 0 000 1.5h6.018c.835.187 1.503.464 1.951.81.439.34.647.725.647 1.197 0 .428-.159.895-.594 1.267-.444.38-1.254.726-2.676.726-1.373 0-2.38-.493-2.86-.956a.75.75 0 00-1.042 1.079C3.992 13.393 5.39 14 7.096 14c1.652 0 2.852-.403 3.65-1.085a3.134 3.134 0 001.12-2.408 2.85 2.85 0 00-.811-2.007z"/></svg>