Brief summary of changes

• Adds multi-select controls to the Issue Tracker Batch Edit tab.
• Adds batch editing for issue status, priority, category, and assignee.
• Adds a dedicated BatchEdit endpoint for retrieval, validation, and atomic updates.
• Restricts BatchEdit GET and POST requests to users with the all-sites issue permission.
• Preserves issue history, close permissions, watchers, and notifications during batch updates.
• Adds translation template entries, integration coverage, and manual testing instructions.

Testing instructions

• Open http://localhost:8080/issue_tracker/ as a user with the Issue Tracker: View/Edit/Comment Issues - All Sites permission.
• Open the Batch Edit tab and confirm issues, assignees, watchers, and comments load.
• Filter the issues and confirm Select all filtered issues selects only matching issues.
• Select issues across multiple pages and confirm the selection is preserved.
• Change status, priority, category, and assignee, then apply the changes.
• Confirm fields set to No change retain their original values.
• Set category to Uncategorized and assignee to Unassigned and confirm both values are cleared.
• Open an updated issue and confirm the changed fields and Last Updated By appear in its history.
• Confirm newly assigned users are added as watchers.
• Confirm Closed and Rejected respect the existing Issue Tracker close permissions.
• Confirm a user with only the own-sites issue permission cannot access the BatchEdit endpoint.

Link(s) to related issue(s)

• Resolves [issue_tracker] Batch Edit Mode batch edit status/priority/category #10773
• Resolves [issue_tracker] extract the batch-edit from the Edit class #10810