Redirect for W3C well-known password change URI

**Is your feature request related to a problem? Please describe.**
While still not widely deployed, there is more visibility being given to the (relatively) new W3C draft for a [`.well-known` URI that redirects to the site's password change functionality](https://w3c.github.io/webappsec-change-password-url/). It is a nice convenience feature for sites and services that support it, to quickly go to the account management page to change/update a password and other credentials.

**Describe the solution you'd like**
Redirect `authentik.tld/.well-known/change-password` to the tenant change password flow. This may require extra configuration from the system administrator to allow the flow to be accessed by logged out users, but I think that should be left as an exercise of the implementer.

**Describe alternatives you've considered**
Redirect manually with reverse proxy, but unless the API is called, you must hard-code the path to the flow.

**Additional context**
This is very low priority but should be very easy to implement.