Allow ebulk to run in "always yes" mode

The new command argument -y (--yes) allows to run ebulk without dialog inputs, it assumes user inputs always yes.

Considerations and assumptions about this feature:

• syntax: ebulk pull/push [args] -y
• the "-y" (or --yes) argument must go at the end of the full command
• for standard operations like fresh uploads/downloads, the user dialogs are automatically skipped with 'yes' input
• for complex scenarios like interrupted operations, conflicts, existing files, etc. it will override by default and start operations from scratch
• -y doesn't apply for scenarios that are not intended to be automated, like staging, discarding changes, etc.

This MR also has some minor bug fixes and code cleanup.