Add an optional label or notes field to redirects

Problem/Motivation

When using redirects for legacy URLs or for marketing campaigns, it would be super helpful to have a field where you can label the redirect or leave a note to inform other site builders for what reason this redirect was created.

Automatically generated redirects could then also leave a generic text to show that this was auto-generated by a path change for example.

If this is an option for the maintainers, we'd be happy to implement a MR, but first I'd like to wait for your confirmation so that we're not wasting time.

Thank you!

Steps to reproduce

Proposed resolution

Remaining tasks

User interface changes

API changes

Data model changes