feat: suppress spinner in watch command with --silent flag

[egvr2002]

Summary

Fixes #5301

This issue was opened a long time ago, so I don't really know if my fix still applies. However, I decided to work on this and send this PR.

This PR suppresses the animated spinner in netlify watch when the --silent flag is used, preventing continuous terminal activity notifications in some terminal multiplexers like tmux, screen, etc.

However, I have some questions about this feature:

• Should console.time('Deploy time') / console.timeEnd('Deploy time') also respect the --silent flag?
• There's an issue comment that mentions: "We do have a --silent flag (and --json might work here too)". Buuut the watch command currently doesn't have a --json option implemented. Should I add it as part of this PR?

LMK if you need anything else. I'm open to feedback if the approach or requirements have changed. 😃

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