Custom Backup Directory

## Enhancement Summary
I want to suggest that a new option be added to the directories settings, that lets you choose the location of the .bak files made as backups of project files. Maybe a few on/off buttons that let you choose whether you want to use the custom directory, the default directory, or both as well.

#### Justification
An hour or two ago, I accidentally permanently deleted all my projects, and since the .bak files were in the same directory, they were also deleted. This was probably just me being dumb, but in order to prevent future mess ups like this, I want to suggest this.

#### Mockup
Where it should be added to ⬆️ Just another field to this area that specifies where you want the .bak files to be held and the buttons under that.

How I think it should be formatted ⬆️

### Overall
The only thing that really matters here would be the ability to change where .bak files are saved, but the little bit of customization with the buttons would be nice.

Start by locating the directories settings UI and the code that creates .bak backups; the issue does not name specific files or tests. Define how a custom directory, the default directory, or both should be selected, then verify that project backups are saved according to the chosen setting.

Written by the indexing model from the issue text.