Make sure that all anchors share the same style on hover and focus

Resources

Currently we have some anchors that have a different style for their hover and focus states. I've found two examples so far where this happens:

Time stamps in system notes for Issues and Merge Requests

Hover

Focus

Anchors in the Issue and Merge Request sidebar

Hover

Focus

All the focus states should be made to match the hover state. If anyone finds more examples of this, please add them to this issue.