chore: switched to new build system for css.

- added community.bundle.less file to create css bundle
- removed the obsolete build.json in favor of new build system
- updated the paths in the books
- removed the imported urls from css files (the new build system doesn't support that)
- removed obsolete lms.css

community/public/css/community.bundle.less

@@ -0,0 +1,4 @@
+
+@import "./style.css";
+@import "./vars.css";
+@import "./style.less";