Leverage gitmailmap for fixing authors' names

[peterfpeterson]

This PR gets rid of the custom work for fixing committer/author information to use functionality git already has.

gitmailmap is a built in git functionality for converting the random names/emails that people supply into something more meaningful. This includes correcting the names and email addresses.

There is no associated issue.

To test:

This added the ability to get the authors directly from tools/DOI/authors.py and can be run without accidentally creating a DOI. Use tools/DOI/authors.py --help to find out how to use it and try the two modes. As it says, you need to contact a TWG member (i.e. me) to get the .gitmailmap file.

This does not require release notes* because it modifies how authors are generated for the DOI tool.

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[thomashampson]

I like that you can now run the authors.py script directly to print a list of authors for a given version. However, I think these points need to be addressed:

1. It does not return the names in "last_name, first_name(s)" format, as per the DOI schema.
2. It relies on a .mailmap file existing to map multiple aliases to each author. This would need to be hosted somewhere and updated by the technical release manager each release.
3. Some people may want there DOI author name to differ from their github name (e.g. Rob might want his formal name Robert to be his author name). This information is already captured in the existing translations list, and would need to be replicated in the mailmap.

[peterfpeterson]

All your points are quite valid. This moves the responsibility of correctly referring to committers to the mailmap file, which is maintained separately. Changes to the mailmap are as frequent as editing the existing script currently is. We could address the issues of the naming conventions in the mailmap file, but that assumes we stick with this approach. The bad part of using the mailmap is that we have to share/sync it separately.

A totally separate question I have is how we could use this to update the CITATION.cff and associate orcid for committers that have them. That is not for this issue.

[peterfpeterson]

This is replaced by #40633