Feat/multiple site jobs

[disha-itpl]

Description

This PR introduces multi-site job support for common site operations, allowing the same action to be performed on multiple sites in a single Helm release.

What’s included

• Add create-multiple-sites job to create multiple sites via Helm values
• Add drop-multiple-sites job to drop multiple sites via Helm values
• Add migrate-multiple-sites job to migrate multiple sites via Helm values
• Add backup-multiple-sites job to back up multiple sites via Helm values

Job precedence & toggles

• Each multi-site job is paired with its existing single-site job
• Only one job (single-site or multi-site) is expected to run at a time
• If both single-site and multi-site jobs are enabled, the single-site job takes precedence, and the multi-site job is skipped

Backward compatibility

• No existing values or workflows are broken
• Upgrading users can opt in to multi-site jobs without changing current setups

Migration note

• Users can migrate from create-site to create-multiple-sites by moving the existing site configuration into the multi-site list (along with additional sites, if required)

Fixes

Closes #271