Add ability to mount volumes

**Is your feature request related to a problem? Please describe.**
I use toolbox in fedora silverblue. I want to install dotnet sdk into a toolbox and than expose it to host for using with IDE. I can call `dotnet` command using `toolbox run`, but I also need access on host to files of sdk that are installed into `/usr/lib64/sdk/dotnet`.

**Describe the solution you'd like**
This can be solved with volumes: I will create `/home/user/dotnet:/usr/lib64/sdk/dotnet` mount and use it in my IDE

**Describe alternatives you've considered**
I tried to mess with podman:
- add volume to an existing toolbox (not possible)
- create a new container from toolbox image (but to be usable toolbox must configure this container first, and I didn't figure out how to do this)
- commit existing toolbox container and run a new one from this image (throws errors on starting and fails)

**Additional context**
There was a PR #100 that can support this, but it was closed without implementation many years ago