[feature request] Showing available disk space in /home/user volume

## Prerequisites
- [X] I have searched open and closed issues for duplicates.

## Feature
`Files` showing available disk space in `/home` volume

**Describe the solution you'd like**
Either a bottom bar on the `Files` window that could poll available disk / volume space on opening `Files` or after a _copy / delete_ file operation, **or** a small _progress-bar_ type indicator under the _home directory_ icon (perhaps more in line with _elementary OS'_ interface guidelines).


Right now, I have to go to the terminal to do `df -h` to see how much space I have left on my `/home/user` volume.
I can see a _progress-bar_ style indicator for _Filesystem_ on the left sidebar, but that shows the available space on `/` when hovering with the mouse cursor, which isn't of much userspace concern.