feat: add starship plugin

[pbr0ck3r]

What kind of change does this PR introduce? (Bug fix, feature, docs update, ...) Feature: New plugin

What is the current behavior? (You can also link to an open issue here) N/A, plugin is not installed/configurable by Fig.

What is the new behavior (if this is a feature change)? Allows the installation of Starship through Fig and configuring the source starship.toml file.

Additional info: Install docs can be found here: https://starship.rs/guide/#%F0%9F%9A%80-installation