Add FreshRSS widget (#1377)

* feat: add FreshRSS widget

* refactor: revert credentialed.js

* refactor: custom proxy handler for FreshRSS

* refactor: cache the token as long as possible

During installation, the salt is generated and remains constant unless
the user re-installs the FreshRSS instance.

src/widgets/components.js

@@ -17,6 +17,7 @@ const components = {
   emby: dynamic(() => import("./emby/component")),
   fileflows: dynamic(() => import("./fileflows/component")),
   flood: dynamic(() => import("./flood/component")),
+  freshrss: dynamic(() => import("./freshrss/component")),
   ghostfolio: dynamic(() => import("./ghostfolio/component")),
   gluetun: dynamic(() => import("./gluetun/component")),
   gotify: dynamic(() => import("./gotify/component")),