Componentise pop-over for reusability and consistent usage, (make on hover default functionality)

Problem

Currently we have 2 different kinds of pop-overs in our application:

• On hover - implemented with the blue dot functionality
• On click - implemented with the gpg signed commits feature

https://gitlab-org.gitlab.io/design.gitlab.com/components/popovers states that we should have it function on hover by default.

Aside from that, there seems to be technical debt surrounding this functionality as it was not easily reusable. I propose we make a proper component out of pop-overs and replace existing implementations.