add Merge Confidence badges behind pending upgrades on dashboard

[HonkingGoose]

I was looking through a Renovate dashboard for a big project, and I noticed they have a lot of major upgrades pending. It would be nice if the Renovate bot can tell you on the dashboard about the confidence level of pending upgrades. So that a team that's behind on upgrades can pick high confidence upgrades first.

I was thinking of adding a badge for all fields, but that would only clutter things up. I think using the Merge Confidence badge alone is probably enough.

A badge with "low/neutral/high/very high", for a quick at-a-glance feel of whether the upgrade will be "hard" or "easy" to merge. I don't know how to get different badges for my mock-up, so I'm grabbing them from a Renovate PR.

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Mockup time:

This issue contains a list of Renovate updates and their statuses.

Pending Approval

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• [ ] build(deps): update dependency aws-sdk to v2.812.0
• [ ] build(deps): update dependency ini to v2
• [ ] chore(deps): update dependency @types/markdown-it to v12

Awaiting Schedule

These updates are awaiting their schedule. Click on a checkbox to ignore the schedule.

• [ ] chore(deps): update mcr.microsoft.com/vscode/devcontainers/typescript-node docker tag to v0.154.0
• [ ] chore(deps): lock file maintenance (no badge because of multiple deps)

Pending Status Checks

These updates await pending status checks. To force their creation now, check the box below.

• [ ] build(deps): update dependency commander to v6.2.1
• [ ] build(deps): update dependency got to v11.8.1
• [ ] build(deps): update dependency ini to v1.3.8
• [ ] chore(deps): update linters (@typescript-eslint/eslint-plugin, @typescript-eslint/parser, eslint, eslint-plugin-jest) (no badge because of multiple deps)

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