[Feature] Allow users to specify their `projects` directories

[dylankenneally]

Is your feature request related to a problem?
I tend to keep my projects at ~/git, this means ClearDisk does not account for them under the Projects tab as seen in the screenshot below.

Describe the solution you'd like
Could users be given the means of specifying their project directories so they can be included in ClearDisk's scanning?

Additional context