Use GlTooltip component on repository file list
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### Problem to solve
When navigating the repository view, hovering the "Last commit" information for a given file/fold presents the user with a "popover" that provides more details about the commit. This does not appear to match the styling of our [tooltip](https://design.gitlab.com/components/tooltip) or [popover](https://design.gitlab.com/components/popover) components.
### Proposal
Use [gl-tooltip component](https://design.gitlab.com/components/tooltip) to display the additional information for the "last commit" in the repository view.
issue