Support for `git show rev:path`

**Is your feature request related to a problem? Please describe.**
I'd like to see how a file looks at a specific revision. Like in `git show rev:path`.

**Describe the solution you'd like**
Two fold:
- From the diff window, be able to switch between diff mode and full-content mode
- From the commits window, be able to fuzzy-find a file in that commit and see how it looks like there

**Describe alternatives you've considered**
N/A

**Additional context**
N/A

Thanks for your 🔝 work on this project