Add support for packages into quasiquotes and toolbox, improve handling of fresh names, unhardcode quasiquote expansion logic

Fixes:

- SI-6841 & SI-6657 by adding support for packages into quasiquotes and toolbox
- handling of fresh names that could have been generated by parser in quasiquotes
- unfortunate `isCaseDefStart` method name
- unhardcodes quasiquote expansion logic
- typos and various inconsistencies

Review by @retronym