Add template_fields to SalesforceBulkOperator

[neooooo28]

Summary

• Adds template_fields to SalesforceBulkOperator so Jinja templating works on operation, object_name, payload, and external_id_field parameters
• Adds a test to verify the template_fields tuple is defined correctly
• Follows the same pattern used across other Airflow operators

Closes #62375

Test plan

• Added unit test verifying template_fields tuple contents
• Existing Salesforce provider tests pass without modification

🤖 Generated with Claude Code

[boring-cyborg]

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