Install Starship everywhere

Summary:
Snap allows to install Starship on linux too,
even for Fedora and Debian where it's not distro-packaged.

Fixes T1539.

Test Plan: Test on Eglide

Reviewers: dereckson

Reviewed By: dereckson

Maniphest Tasks: T1539

Differential Revision: https://devcentral.nasqueron.org/D2145