The --auth-token argument is hidden from the sentry-cli monitors run subcommand since the command uses DSN authentication, however passing the argument is still possible (it is simply ignored).

However, providing this argument causes a panic with a not-very-user-friendly message, since the argument was defined here without the auth token parser, and we attempt to read the auth token as an AuthToken.

This PR fixes the bug.

Fixes #2170

The anyhow crate we use for error handling adds stack backtraces errors whenever certain standard environment variables are set (e.g. when RUST_BACKTRACE=1).

Modify our error-printing logic to include these stack backtraces when printing errors that crash Sentry CLI, so that users can add this information to bug reports.

Closes #2187