Allow to skip to CheckForUpdate

[yellowhat]

Summary

Hi,
I noticed that on startup newt is making request to api.github.com to check for new version.

Would it be possible to add a -no-update-check flag?

Motivation

Some people might use external tool to check for latest tag.
For Air-gapped environments, the request will always fail and log an error, adding noise.

Proposed Solution

Add -no-update-check that skips the updates.CheckForUpdate call.

Alternatives Considered

No response

Additional Context

No response