[PLAT-18637]Add option to use signing region in storage config cr

Summary:
Signing regions are useful for S3 compatible endpoints as well as private S3
endpoints. Added ability to specify that in Storage config crd.

Test Plan: itests

Reviewers: anijhawan, dshubin, anabaria

Reviewed By: anabaria

Differential Revision: https://phorge.dev.yugabyte.com/D47074

Author: kv83821-yb

managed/src/main/java/com/yugabyte/yw/common/operator/resources/storageConfigCrd.yaml

@@ -94,6 +94,11 @@ spec:
                         Use path style access for S3 bucket configuration. Valid for S3 compatible
                         storages.
                       type: boolean
+                    SIGNING_REGION:
+                      description: |
+                        Signing region to be used for S3 clients when accessing storage bucket. Use
+                        for S3 compatible storages / private S3 endpoints.
+                      type: string
                   required:
                   - BACKUP_LOCATION
                 awsSecretAccessKeySecret: