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 terminal multiplexers (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)". 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. 😃

For us to review and ship your PR efficiently, please perform the following steps:

• Open a bug/issue before writing your code 🧑‍💻. This ensures we can discuss the changes and get feedback from everyone that should be involved. If you`re fixing a typo or something that`s on fire 🔥 (e.g. incident related), you can skip this step.
• Read the contribution guidelines 📖. This ensures your code follows our style guide and
  passes our tests.
• Update or add tests (if any source code was changed or added) 🧪
• Update or add documentation (if features were changed or added) 📝
• Make sure the status checks below are successful ✅