feat(config): allow restriction and disabling of uploads

Previously, image uploads were always allowed, unless `CMD_ALLOW_ANONYMOUS=false` and `CMD_ALLOW_ANONYMOUS_EDITS=false`.
This PR adds a new config option `CMD_ENABLE_UPLOADS` to configure image uploads independently. There are three different modes: `all` (everyone can upload, guests too), `registered` (only registered and logged-in users can upload images), and `none` to completely disable image uploads.
The default value is non-breaking as it is `all`, unless the config `CMD_ALLOW_ANONYMOUS=false` and `CMD_ALLOW_ANONYMOUS_EDITS=false` is set, in which case the value is `registered`.
The UI will reflect the setting and either show or hide the upload button.

Signed-off-by: Erik Michelson <github@erik.michelson.eu>

lib/web/statusRouter.js

@@ -111,7 +111,8 @@ statusRouter.get('/config', function (req, res) {
     DROPBOX_APP_KEY: config.dropbox.appKey,
     allowedUploadMimeTypes: config.allowedUploadMimeTypes,
     linkifyHeaderStyle: config.linkifyHeaderStyle,
-    cookiePolicy: config.cookiePolicy
+    cookiePolicy: config.cookiePolicy,
+    enableUploads: config.enableUploads
   }
   res.set({
     'Cache-Control': 'private', // only cache by client