Allow Tailscale to be set up from within TinyPilot

[cghague]

Tailscale is one of the most popular remote access solutions used by TinyPilot customers. It would be good if we could offer a way to set it up via the TinyPilot app. This feature could reduce support load as users wouldn't need to run through enabling SSH and completing the terminal-based installation process.

One approach for implementing this would be adding a "Tailscale" item to the new "Network" submenu. This item would reveal an information dialog with an "Enable" button. Pressing the "Enable" button would cause TinyPilot to automatically install Tailscale, grab the magic join link, and display it until the user dismisses the dialog. If the user revisits the dialog, we'd offer a "Remove" option, which would uninstall Tailscale.