Install tmux plugins (tpm)

[ScottG489]

tpm plugins need to be installed in tmux (typically by pressing prefix - I). We should do this installation during the provisioning rather than needing the user to do it manually.

I tried to get this working but I wasn't able to. Here is one resource which seemed promising but didn't work:

https://github.com/tmux-plugins/tpm/blob/master/docs/automatic_tpm_installation.md

Also the command run from tmux is: run-shell /home/scott/.tmux/plugins/tpm/bindings/install_plugins

I wasn't able to get anything working though unfortunately.