Custom user avatars from upload, LDAP jpegPhoto, or a blueprint path

## What

custom/dynamic user avatars (upload, LDAP jpegPhoto, blueprint-provisioned path) instead of Gravatar-only.

## Want

- Custom/dynamic user avatars (upload, LDAP jpegPhoto, blueprint-provisioned path) instead of Gravatar-only

## Ideas this came from

- [#2631 Custom avatar pictures](https://github.com/goauthentik/authentik/issues/2631) — I want to use neither Gravatar nor a completely custom avatar system, but rather the jpegPhoto field of LDAP, and want to be able to change that picture in the
- [#11425 Provision System>>Settings>>Avatars via blueprints](https://github.com/goauthentik/authentik/issues/11425) — I checked https://goauthentik.io/blueprints/schema.json and found these available models:

No files, tests, or entry points are named. Start by locating the existing Gravatar-only avatar handling and the LDAP and blueprint provisioning paths; done would require a defined, tested approach for uploaded avatars, LDAP jpegPhoto avatars, and blueprint-provisioned avatar paths.

Written by the indexing model from the issue text.