feat: G15Office job, widget settings and submissions admin, embed.js and the settings importer

- SyncG15Office files each submission as a G15Office task with its screenshot through a fetchguard client limited to the configured host; a River job with 3 attempts, PHP's messages on failure, nothing sent when unconfigured
- the replay of PHP's recorded G15Office exchange (classes/testdata) asserts the task JSON, headers and the screenshot part
- settings screen (cabana field types only), read-only submissions list, manage_settings permission and navigation
- embed.js served byte for byte at /plugins/golem15/feedback/assets/js/embed.js
- feedback:import-settings copies the WinterCMS settings row once

controllers/submissions/config_list.yaml

@@ -0,0 +1,13 @@
+list: ~/plugins/golem15/feedback/models/submission/columns.yaml
+modelClass: Golem15\Feedback\Models\FeedbackSubmission
+title: golem15.feedback::lang.submissions.list_title
+noRecordsMessage: backend::lang.list.no_records
+recordsPerPage: 20
+showCheckboxes: false
+defaultSort:
+    column: created_at
+    direction: desc
+
+toolbar:
+    search:
+        prompt: backend::lang.list.search_prompt