fix: allow frontend visibility for integrations itself

Currently, `integrations` is retrieved at catalog-import to check
configured integrations.

This could fail if there was no config below `integrations` which has `@visibility frontend`.

This happened if no integration or only non-Github integrations without
frontend visible properties like `integrations.bitbucketCloud` are used.

After this change, at least `integrations` will always be visible to the frontend.

Closes: #11700
Signed-off-by: Patrick Jungermann <Patrick.Jungermann@gmail.com>

.changeset/sweet-plants-sparkle.md

@@ -0,0 +1,5 @@
+---
+'@backstage/integration': patch
+---
+
+Allow frontend visibility for `integrations` itself.

packages/integration/config.d.ts

@@ -15,7 +15,10 @@
  */
 
 export interface Config {
-  /** Configuration for integrations towards various external repository provider systems */
+  /**
+   * Configuration for integrations towards various external repository provider systems
+   * @visibility frontend
+   */
   integrations?: {
     /** Integration configuration for Azure */
     azure?: Array<{