feat(sltt-app): provide a disk volume api so that the client can use StorageLimitStatus to warn user when disk space is low

[ericpyle]

The api needs to be able to return the volume's capacity, how much disk space is used, and how much is available.

We could just add this to our storage api, see storage/index.ts. Create a new file called storage/volumes.ts or something like that that can be imported into storage/index.ts.

getSlttAppVolumeStats should return the capacity and usage and available stats for the same volume that sltt-app is installed on.

In the future, we'll need to extend this for LAN storage to help user know how much storage is available on their LAN storage device, and to provide stats for other possible storage locations (for probeLANConnections)

[EllisBenus]

The compressor already has a calculation for the disk space, so it would be nice to utilize this.

• There's already an api in the compressor that gives the disk space
• Call the Free Space API in the compressor from the client, so within the context of the client we're using the api, and if this fails then we know the compressor is not running. There should already be code in the client that will tell you whether the compressor is running.
• If they are running the compressor server, we should take advantage of that. If they aren't...

Would need to open an issue for the client (not electron) to get the low disk space warning issue working.

Created a branch for this: https://github.com/ubsicap/sltt-app/tree/feat-38-disk-volume-api

This issue is likely not needed any longer because if we make the code work correctly, using the compressor, in the client then it will "automatically" work in the electron app.

[EllisBenus]

added /storage/volumes.ts with the function getSlttAppVolumeStats and the output gave me the correct information

I did have to use a mock value to force the app.getPath('userData') to be C:\Users\ellis\AppData\Roaming\sltt-app because the vitest does not have the userData.

The below data is from the test we ran. Next I have to get the app to actually run this code rather than just the test.

[ericpyle]

I added diskUsage as part of the probeConnections response (see #54)