integrations: add allowedInstallationOwners to config schema

Signed-off-by: Patrik Oldsberg <poldsberg@gmail.com>

.changeset/weak-ears-jam.md

@@ -0,0 +1,5 @@
+---
+'@backstage/integration': patch
+---
+
+Added `integrations.github.apps.allowedInstallationOwners` to the configuration schema.

packages/integration/config.d.ts

@@ -189,6 +189,14 @@ export interface Config {
          * @visibility secret
          */
         clientSecret: string;
+        /**
+         * List of installation owners allowed to be used by this GitHub app. The GitHub UI does not provide a way to list the installations.
+         * However you can list the installations with the GitHub API. You can find the list of installations here:
+         * https://api.github.com/app/installations
+         * The relevant documentation for this is here.
+         * https://docs.github.com/en/rest/reference/apps#list-installations-for-the-authenticated-app--code-samples
+         */
+        allowedInstallationOwners?: string[];
       }>;
     }>;