Add the option to generate a project with the git version of embassy

[AdinAck]

Hmm, that process is usually bespoke for the application.

How do you propose this feature would look?

[KapDecy]

I suggest adding the “--git” flag, when used, embassy dependencies will be added to Cargo.toml with “git = ‘https://github.com/embassy-rs/embassy.git’” rather than with version