feat: check for tool updates when printing current version

[MatteoPologruto]

Motivation

Users should know if a new version of the tool is available.

Change description

A message is printed if a new version of the tool is available when checking the current version:

$ ./build/arduino-flasher-cli version
Arduino Flasher CLI 0.0.0-d6bef23


A new release of Arduino Flasher CLI is available: 0.0.0-d6bef23 → 0.3.0
https://github.com/arduino/arduino-flasher-cli/releases/latest

Additional Notes

Reviewer checklist

• PR addresses a single concern.
• PR title and description are properly filled.
• Changes will be merged in main.
• Changes are covered by tests.
• Logging is meaningful in case of troubleshooting.

[dido18]

I would display a notification about a new version being available before every command, not only when running the version command.

The update check should be non-blocking — if an error occurs during the check, a general warning should be shown without preventing the command from running.