feat: configurable favicon service URL (#659)

src/lib/faviconUrl.ts

@@ -0,0 +1,19 @@
+import UriTemplate from 'uri-templates'
+
+export function faviconUrl(template: string, url: string | URL): string {
+  const u = new URL(url)
+
+  return UriTemplate(template).fill({
+    href: u.href,
+    origin: u.origin,
+    protocol: u.protocol,
+    username: u.username,
+    password: u.password,
+    host: u.host,
+    hostname: u.hostname,
+    port: u.port,
+    pathname: u.pathname,
+    hash: u.hash,
+    search: u.search
+  })
+}