IndieAuth provider in Authentik

**Is your feature request related to a problem? Please describe.**
Not related to a problem

**Describe the solution you'd like**
I'd like to be able to add a meta tag to my website that directs IndieAuth SPs to my Authentik installation to authenticate me using IndieAuth.

**Describe alternatives you've considered**
I'm aware there's some level of overlap between this and OpenID Connect, but it seems like more services I use support IndieAuth than URL-based (non-oauth) OpenID Connect, so it would be nice to have.

**Additional context**
I'm currently using my personal Wordpress installation with the SAML and IndieAuth plugins to "proxy" IndieAuth to Authentik (Effectively making my Wordpress install both a SAML SP and an IndieAuth IdP). The motivation for this request is to cut out the middle-man and reduce chances of breakage or attacks.