Make sure all buttons turn dark on focus

Currently we have some buttons that have a different style for their hover and focus states.

I've found two examples so far where this happens:

Add Todo button in Issue and MR sidebar

Default

Hover

Focus

New milestone button in Milestones view

Default

Hover

Focus

The darkening should be added to the focus states. If anyone finds more examples of this, please add them to this issue.

Mentioned in issue #24063 (moved)

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@cperessini does this need the %8.14 milestone? Will this be implemented/ready for ~Frontend ?

Mentioned in merge request !7546 (closed)

This issue seems fixed on master. Can you confirm @cperessini ?

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@tauriedavis The two buttons I mentioned are fixed, thanks! I'm closing this issue for now, we can reopen if we find any other instances where this happens.

Status changed to closed

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mentioned in issue gitlab#6851