No default workspace dashboard

[mikegros]

Problem:

• The URSA dashboard makes default workspaces in the .cache/ursa//dashboard/sessions directory. This is hard to reach for non-technical users and a bit awkward for anyone.

Fix:

• When users create a new session, they are prompted to pick a workspace folder or select a temporary folder.
• This forces users to pick a location for the work but in a smooth, natural manner so they know where files will go.

Legacy behavior:

• For cases where the user used a default workspace in .cache before, ursa will prompt the user to select a workspace but default to the random one in cache, so the user does not lose track of their previous work, but now has explicitly selected where it is.