fix(gateway): more descriptive project not found error

[fatfingers23]

Description of change

Added the project name that is attempted to be used when looking up the status of a project in the error message.

I added the feature flag backend to the cargo-shuttle/Cargo.toml, because it appears it needed it for a test. I debated removing the feature flag from project.rs for what was required but decided to leave it. If this is not the desired outcome, please let me know, and I will update the PR

Closes #1397

How has this been tested? (if applicable)

Ran the command cargo run --bin cargo-shuttle -- project status --name ibetthisnameisnttaken as suggested in the issue and got the project name in the new error message.

[jonaro00]

Thanks for the PR!
Having backend enabled from cargo-shuttle is not desired, so if there's an easy refactor you can try it. You can also compromise and turn the enum type into ProjectNotFound(String) as the newtype isn't needed in the context of errors.

[fatfingers23]

Ended up taking the compromise and used String instead. Was the path with the least amount of changes and seemed what was appropriate since it's for an error message

[jonaro00]

LGTM

[oddgrd]

Great, thanks!