feat(cli): Add available version checking

[owenrumney]

Description

Adds a background check to https://api.trivy.cloud/check to see if there is new version or any relevant notices available.

The check will be suppressed if the user uses the --no-notices or --quiet envvars or flags. The docs have been updated with the new notices flag

Example output

Although the image shows dummy versions, the api has been updated to reflect the correct information and has no announcements at this time... just the latest version (0.60.0)

Related issues

• Closes #8552
• Closes #8732

Checklist

• [X] I've read the guidelines for contributing to this repository.
• [X] I've followed the conventions in the PR title.
• [X] I've added tests that prove my fix is effective or that my feature works.
• [X] I've updated the documentation with the relevant information (if needed).
• [X] I've added usage information (if the PR introduces new options)
• [X] I've included a "before" and "after" example to the description (if the PR is a user interface change).