GLSP-1320: Update to latest glsp dev config (#206)
* GLSP-1320: Update to latest glsp dev config
- Updates to latest version of dev,client & server packages - Add temporary resolution - Add generate:index utility script - Regenerate index files - Fix codeActionsOnSave in vscode settings - Refactor upgrade:next script - Reformat code base with prettier - Fix copyright headers (by running a full check with glsp checkHeaders . -t full)