From: anpl1623 <andrewpleeter@gmail.com>

Add a builtin 'whoami' command to inspect and display the resolved
author and committer identity along with the commit signing
configuration (GPG/SSH key ID and commit.gpgsign status) used when
creating Git commits.

Support optional flags (--author, --committer, --name, --email,
--signing-key, and --verbose) for targeted querying and scripting.

Include documentation in Documentation/git-whoami.adoc and regression
tests in t/t0015-whoami.sh.

Signed-off-by: anpl1623 <andrewpleeter@gmail.com>

Submitted-As: https://lore.kernel.org/git/pull.2388.git.git.1787690802942.gitgitgadget@gmail.com