FIX: Only block local edits for git-sourced themes (#11450)

Themes uploaded as zip files are given a row in the `remote_themes` table to store metadata, even though they are not truly remote.

app/assets/javascripts/admin/addon/routes/admin-customize-themes-edit.js

@@ -28,7 +28,7 @@ export default Route.extend({
     const fields = wrapper.model
       .get("fields")
       [wrapper.target].map((f) => f.name);
-    if (wrapper.model.remote_theme) {
+    if (wrapper.model.remote_theme && wrapper.model.remote_theme.is_git) {
       this.transitionTo("adminCustomizeThemes.index");
       return;
     }

app/assets/javascripts/admin/addon/templates/customize-themes-show.hbs

@@ -201,7 +201,7 @@
     {{/d-section}}
   {{/if}}
 
-  {{#unless model.remote_theme}}
+  {{#unless model.remote_theme.is_git}}
     <div class="control-unit">
       <div class="mini-title">{{i18n "admin.customize.theme.css_html"}}</div>
       {{#if model.hasEditedFields}}