Add zero-config self hosting on Render (#612)

* v1 of backend implementation for self hosting

* Add docs

* Add upgrades controller

* Add global helpers for self hosting mode

* Add self host settings controller

* Conditionally show self hosting settings

* Environment and config updates

* Complete upgrade prompting flow

* Update config for forked repo

* Move configuration of github provider within class

* Add upgrades cron

* Update deploy button

* Update guides

* Fix render deployer

* Typo

* Enable auto upgrades

* Fix cron

* Make upgrade modes more clear and consistent

* Trigger new available version

* Fix logic for displaying upgrade prompts

* Finish implementation

* Fix regression

* Trigger new version

* Add i18n translations

* trigger new version

* reduce caching time for testing

* Decrease cache for testing

* trigger upgrade

* trigger upgrade

* Only trigger deploy once

* trigger upgrade

* If target is commit, always upgrade if any upgrade is available

* trigger upgrade

* trigger upgrade

* Test release

* Change back to maybe repo for defaults

* Fix lint errors

* Clearer naming

* Fix relative link

* Add abs path

* Relative link

* Update docs

config/locales/models/upgrader/en.yml

@@ -0,0 +1,13 @@
+---
+en:
+  upgrader:
+    deployer:
+      null_deployer:
+        success_message: 'No-op: null deployer initiated deploy successfully'
+      render:
+        deploy_log_error: 'Failed to deploy %{type} %{commit_sha} to Render: %{error_message}'
+        deploy_log_info: Deploying %{type} %{commit_sha} to Render...
+        error_message_failed_deploy: Failed to deploy to Render
+        error_message_not_set: Render deploy hook URL is not set
+        success_message: 'Triggered deployment to Render for commit: %{commit_sha}'
+        troubleshooting_url: https://render.com/docs/deploy-hooks