Feature/sideload (#1520)

* base styling and action placeholders for package sideload

* apparently didnt add new folder

* wip

* parse manifest and icon from s9pk to upload

* wip handle s9pk upload

* adjust types, finalize actions, cleanup

* clean up and fix data clearing and response

* include rest rpc in proxy conf sample

* address feedback to use shorthand falsy coercion

* update copy and invalid package file ux

* do not wait package upload, instead show install progress

* fix proxy for rest rpc

rename sideload package page titles

frontend/proxy.conf-sample.json

@@ -12,5 +12,11 @@
     "pathRewrite": {
       "^/public": ""
     }
+  },
+  "/rest/rpc/*": {
+    "target": "http://<CHANGE_ME>/rest/rpc",
+    "pathRewrite": {
+      "^/rest/rpc": ""
+    }
   }
 }