Customize format for last-commit badge

:clipboard: **Description**

Can we add a query parameter, say `f` which will send to `moment.format(f)`, to control the date format? Maybe not only last-commit badge, but also other date related badges.

My real use-case is a little special. There is a repository, [Bogdanp/awesome-advent-of-code](https://github.com/Bogdanp/awesome-advent-of-code), which collects solutions for a programming puzzle activity. Because the activity is only hold in December every year. It's not easy to distinguish last-commit date among those solution repositories.

Locate the last-commit badge entry point and the handling for date-related query parameters, then compare any other date badges that may share the same logic. The change is complete when the `f` parameter is passed to `moment.format(f)` for the last-commit date and tests cover the requested formatting behavior.

Written by the indexing model from the issue text.