Hot Exit: deal with backup workspaces that do not exist anymore

[bpasero]

On startup you add workspaces to open that have backups. What if this workspace meanwhile got deleted? You should check this on startup and remove the backup workspace from workspaces.json if you detect it does not exist anymore.

[Tyriar]

👎 to removing backups unannounced under any circumstances. I would expect the folder to be opened like it currently is, ideally with a dialog asking if the user wants to restore backups on a deleted workspace..

[bpasero]

@Tyriar agree, but we are currently not able to open the folder if it does not exist so best you could do is to open a bunch of untitled files that point to the folder. I will update the title of this issue.

[bpasero]

Actually the title of this issue is still good, but the fix for this issue is more complicated to prevent loosing user data.

[Tyriar]

This is what happens right now.

1. 
2. rm ../temp-workspace
3. 

[bpasero]

@Tyriar it seems to me the file that was previously "test file" is now called "temp-workspace"? path issues?