Add a page listing people someone follows (#444)

Nothing exceptional, the layout is the same as the followers page.

Fixes #325

templates/users/followed.rs.html

@@ -0,0 +1,26 @@
+@use templates::{base, users::header};
+@use template_utils::*;
+@use plume_models::users::User;
+@use routes::*;
+
+@(ctx: BaseContext, user: User, follows: bool, is_remote: bool, remote_url: String, followed: Vec<User>, page: i32, n_pages: i32)
+
+@:base(ctx, i18n!(ctx.1, "{0}'s subscriptions'"; user.name(ctx.0)), {}, {}, {
+    @:header(ctx, &user, follows, is_remote, remote_url)
+
+    @tabs(&[
+        (&uri!(user::details: name= user.get_fqn(ctx.0)).to_string(), i18n!(ctx.1, "Articles"), true),
+        (&uri!(user::followers: name = user.get_fqn(ctx.0), page = _).to_string(), i18n!(ctx.1, "Subscribers"), false),
+        (&uri!(user::followed: name = user.get_fqn(ctx.0), page = _).to_string(), i18n!(ctx.1, "Subscriptions"), false)
+    ])
+
+    <div class="cards">
+        @for follow in followed {
+            <div class="card">
+                <h3><a href="@uri!(user::details: name = follow.get_fqn(ctx.0))">@follow.name(ctx.0)</a> <small>@format!("@{}", follow.get_fqn(ctx.0))</small></h3>
+                <main><p>@Html(follow.summary)</p></main>
+            </div>
+        }
+    </div>
+    @paginate(ctx.1, page, n_pages)
+})