feat(spin): add new module for Spin

[ThorstenHans]

Description

This PR adds a new module for Spin, allowing Spin users to display the currently installed version of the Spin CLI in their prompt.

Motivation and Context

As a developer using Spin to build WebAssembly applications, I want to display the current version of Spin as part of my prompt. This is especially useful for Spin users that leverage Spin's version manager to switch between multiple versions of Spin on their machine.

Screenshots (if appropriate):

How Has This Been Tested?

I installed Spin CLI on my machine using homebrew (brew install fermyon/tap/spin), and updated my starship.toml by adding:

[spin]
disabled = false
permanent = true

To display the currently installed version of Spin also outside of Spin App directories, I set the permanent option to true.

• [x] I have tested using MacOS
• [ ] I have tested using Linux
• [ ] I have tested using Windows

Checklist:

• [x] I have updated the documentation accordingly.
• [x] I have updated the tests accordingly.