feat: Add option to use committer date instead of author date in commit list view

[DawidPietrykowski]

PR Description

This PR adds an option for the expanded commit list view (enabled after pressing + in commit tab) to show dates based on committer date instead of author date. This is useful for example when trying to understand the origin of a new bug based on time of merge (which often matches committer date due to being updated on rebases).

Please check if the PR fulfills these requirements

• Cheatsheets are up-to-date (run go generate ./...)
• Code has been formatted (see here)
• Tests have been added/updated (see here for the integration test guide)
• Text is internationalised (see here)
• If a new UserConfig entry was added, make sure it can be hot-reloaded (see here)
• Docs have been updated if necessary
• You've read through your own file changes for silly mistakes etc