all: Remove untrusted feature flag (fixes #109) (#7567)

No longer hide the web UI controls for the new untrusted/encrypted
device feature. Testing hasn't been very widespread, but there has been
some and quite a few bugs have been caught and fixed. I believe its time
to not hide it anymore, and cautiously recommend usage. E.g. mention
that the feature hasn't been widely used yet and anyone using it is an
early adopter, but drop the bit about not using it with production data.
We can maybe stress the need for backups in general and especially
using this.

gui/default/syncthing/transfer/localChangedFilesModalView.html

@@ -1,8 +1,12 @@
-<modal id="localChanged" status="info" icon="fas fa-exclamation-circle" heading="{{'Locally Changed Items' | translate}}" large="yes" closeable="yes">
-  <div class="modal-body">
-    <p translate>
+<modal id="localChanged" status="{{localChangedType === 'receiveencrypted' ? 'warning' : 'info'}}" icon="fas fa-exclamation-circle" heading="{{localChangedHeading(localChangedType)}}" large="yes" closeable="yes">
+  <div class="modal-body" ng-switch="localChangedType">
+    <p ng-switch-when="receiveonly" translate>
       The following items were changed locally.
     </p>
+    <p ng-switch-when="receiveencrypted">
+      <span translate>The following unexpected items were found.</span>
+      <span translate translate-value-receive-encrypted="{{'Receive Encrypted' | translate}}">You should never add or change anything locally in a "{%receiveEncrypted%}" folder.</span>
+    </p>
     <table class="table table-striped">
       <thead>
         <tr>