`FileUtils.cd` and `Dir.chdir` cause the working directory to change for the entire process. We run sidekiq jobs, hijacked requests and deferred jobs in threads, which can make working directory changes have unintended side-effects.
- Add a rubocop rule to warn about usage of Dir.chdir and FileUtils.cd
- Added rubocop:disable for scripts used outside the app
- Refactored code using cd to use alternative methods
- Temporarily skipped the rubocop check for lib/backup_restore. This will require more complex refactoring, so I will create a separate PR for review
This reduces chances of errors where consumers of strings mutate inputs
and reduces memory usage of the app.
Test suite passes now, but there may be some stuff left, so we will run
a few sites on a branch prior to merging
