feat: `diff-log`

It shows the diff between 2 logs (with --patch by default), something like:

git diff --no-index <(git log -p --format=%s a) <(git log -p --format=%s b)

This is really useful to verify a rebase (or anything that rewrites history). Especially useful if an interactive rebase doesn't change the final state of a branch (as usual of squash).

An alias is not enough, as there's cases when the user may need to pass extra flags, such as:

• -n3/-3 to limit the output of the logs. There's cases when each log needs an independent n value, so simply repeating the same -n twice is not enough.
• --color-words, to make diff smaller.
• --color-moved{,-ws}. Especially ws, because of its many values.

Start at the existing git-extras command entry points and inspect how commands parse arguments and invoke Git. Define the diff-log command around two log inputs, with patch output by default and support for independent log limits plus the listed diff flags. Done means it can compare rewritten histories and pass those options through as described.