Redirect duplicated topics

[ceolinwill]

Is your feature request related to a problem? Please describe.
We get topics from Wikipedia pages. On Wikipedia, they have an option to redirect duplicated pages to existing ones keeping a default one when they have similar names (e.g. Remote work and remote working should be the same page).

Describe the solution you'd like
Add an option to automatically redirect a topic page to a different one. (E.g. "Remote working" could redirect to "Remote work").

Describe alternatives you've considered
N/A.

Additional context
When a post has a redirected topic, it should be replaced by the new one. For example, when a user adds a "Remote working" topic, it should be replaced by "Remote work" in the background.

This issue should be implemented after #35.