Summary

This PR makes Termination a Diagnostic so that errors emitted from the CLI can be printed nicely using our diagnostic infrastructure.

To achieve that, the following changes have been made:

• Termination is now called CliDiagnostic, it's an enum and it manually implements Diagnostic.
• Each variant of the enum contains a diagnostic that is constructed using the diagnostic macro. That saved lot of work.
• The different variants in CliDiagnostic are now implemented via functions.
• RomeError has been renamed to WorkspaceError
• Making CliDiagnostic a Diagnostic comes with a constraint where, to print it, we need a Console type. Now CliSession::new accepts a mutable reference to Console. The Console object gets created at the beginning of rome_cli/src/main.rs#main and then passed to CliSession. This change is also reflected in the test suite, unfortunately.
• Error now implements the std trait Termination and returns ExitCode::FAILURE if the severity is >= Severity::Error.
• the main() function now returns ExitCode
• thiserror crate is removed
• I updated some of the errors while I was at it; I suggest checking the new snapshots

Test Plan

I manually checked the snapshots and checked that they were correct.
I also ran some error cases locally and ensured that the CLI worked as expected.

Documentation

• The PR requires documentation
• I will create a new PR to update the documentation