Switch to grey unverified badge

Problem to solve

The current green checkmark badge is too easily interpreted as having a verified signature

Proposal

1. The user will see a grey unverified badge for any signatures that are not verified. The text of the badge will read Signed (without the "unverified" caveat). The badge will be gray and will have the icon shown.
2. A tooltip for the badge will display on hover and will read, GitLab is unable to analyze whether this signature is valid or not. Please validate the signature manually before trusting it. (exact text to be confirmed by the Docs team)