Update "Commits" tab datetime tooltip to match MR Widget datetime tooltip format

What does this MR do and why?

For #539203

Updates the render of the date time tooltip on the MR Commits tab to be overrideable.

Uses that override to match the date-time format used by the MR Widget tooltip.

Screenshots or screen recordings

The overview tab MR widgets (including the Merged widget) use a datetime format like: mmm d, yyyy h:MMtt Z

The output is like this:

This is the commit timestamp on the Commits tab:

Before	After

How to set up and validate locally

1. You will need an MR with at least 1 commit.
2. It doesn't really matter what state the MR is in, but for the closest match to the reporting issue, you should merge the MR.
3. See the tooltip datetime format in the Commits tab for an individual commit. Compare to the format on the Overview tab for the MR Widget.

MR acceptance checklist

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