feat: app sharing (now open source!) (#4378)

coderd/database/migrations/000060_app_sharing_level.up.sql

@@ -0,0 +1,12 @@
+-- Add enum app_sharing_level
+CREATE TYPE app_sharing_level AS ENUM (
+	-- only the workspace owner can access the app
+	'owner',
+	-- any authenticated user on the site can access the app
+	'authenticated',
+	-- any user can access the app even if they are not authenticated
+	'public'
+);
+
+-- Add sharing_level column to workspace_apps table
+ALTER TABLE workspace_apps ADD COLUMN sharing_level app_sharing_level NOT NULL DEFAULT 'owner'::app_sharing_level;