MDL-55402 theme_noname: Convert bootstrapbase to bs4
All moodle less files are converted to sass with layouts etc written as mustache templates. Bootstrap 4 sass files are imported to scss/bootstrap. Part of MDL-55071
A major upgrade from 14.10.0 to the 15.0.0 version will be performed on Friday, May 27 starting at 8 pm UTC up to 8.20 pm UTC. A short 20 min downtime is expected.
All moodle less files are converted to sass with layouts etc written as mustache templates. Bootstrap 4 sass files are imported to scss/bootstrap. Part of MDL-55071