Improvements for community contributions

In February 2022, we launched a new feature called community contributions to security advisories.

We have made a handful of changes to the UX based on your feedback:

• Fixed the breadcrumb on unreviewed advisories to more clearly display they are unreviewed.
• Hid the link to submit a community contribution when it is not possible due to OSV constraints.
• Added an information icon clarifying that not all ecosystems are supported.
• Updated the auto-generated PR title to the format "[GHSA-####-####-####] Advisory Name" to be clearer on which advisory its for.
• Fixed a bug that was adding unnecessary noise to the PR diff.
• Added function to auto-post an affirming comment when a contribution is accepted.
• Learn more about the GitHub Advisory Database
• Learn more about GitHub community contributions