Implement global flag `--verbose`

[bacongobbler]

The Hippo CLI implements a global verbosity flag that increases the level of log verbosity:

https://github.com/deislabs/hippo-cli/blob/67f6368fa39d296c3d1b11a93e43bc4c751cba6b/src/cli/mod.rs#L61

This is then passed to env_logger to determine how verbose the CLI should present logs to the user:

https://github.com/deislabs/hippo-cli/blob/67f6368fa39d296c3d1b11a93e43bc4c751cba6b/src/cli/mod.rs#L89

This makes it incredibly simple to debug underlying issues with reqwest or other underlying libraries that use Rust's logging subsystem.

I'd love if there was an equivalent flag for Spin.