feat: [CDS-102304]: Add private key as param when fetching deployment yaml.

[mteodor]

Title: [Component/Feature] Short Description of the Change

Summary:
When using data_source_gitops_agent_deploy_yaml to fetch agent deployment yaml agent token gets regnerated and existing token becomes invalid making agent to get disconnect until new manifest is applied.
This PR adds private key as parm so that existing private key can be used to fetch deployment yaml without regnerating the token.

Details:
Explain the changes in detail, including any relevant context or background information.

Related Issues:
Reference any related issues or tickets

Testing Instructions:
Describe how the changes were tested. Include any test cases or steps to verify the functionality.
Please include the below test scenario with your changes.

• Create the resource and execute terraform apply. (Verify the resource is created)
• Execute terraform apply again without any changes. (Verify no changes should be done)
• Update the resource and execute terraform apply. (Verify the resource updated successfully)
• Remove the content from resource file and execute terraform apply. (Verify the resource has been deleted)
• Add again the resource and execute the terraform apply. (Verify the resource is created)
• Verify the import the resource file is working fine.
• In case of remote entity, Verify for both default and non default branch.

Screenshots:
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Checklist:

• Code changes are well-documented.
• Tests have been added/updated.
• Changes have been tested locally.
• Documentation has been updated.

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• Sub Category Field Check: trigger subcategoryfieldcheck
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