Update provider to modernisation-secrets-read and add modernisation-secrets-read provider

[sukeshreddyg]

A reference to the issue / Description of it

Recently, we created separate GitHub Actions roles for development and test accounts. In the current setup (a PR will be raised soon), an issue arose when running Member Environments workflow —secrets could not be accessed from the Modernisation Platform (MP) account due to the OIDC connection pointing to each member account. This resulted in failures to retrieve the necessary secrets. #8590

How does this PR fix the problem?

To resolve this issue, we have added a provider to assume a role in the MP account that has the necessary permissions to read the secrets. This ensures that secrets are accessed from the MP account regardless of the active OIDC connection in the Member account.

How has this been tested?

Tested Manually and also tested on Member Environment workflow

Deployment Plan / Instructions

Will this deployment impact the platform and / or services on it?

{Please write here}

Checklist (check x in [ ] of list items)

• I have performed a self-review of my own code
• All checks have passed
• I have made corresponding changes to the documentation
• Plan and discussed how it should be deployed to PROD (If needed)

Additional comments (if any)

{Please write here}

[github-actions]

Terraform Plan Summary

core-vpc-test
No changes. Your infrastructure matches the configuration.

[github-actions]

Terraform Plan Summary

core-vpc-development
No changes. Your infrastructure matches the configuration.

[github-actions]

Terraform Plan Summary

core-vpc-preproduction
No changes. Your infrastructure matches the configuration.

[github-actions]

Terraform Plan Summary

core-vpc-production
No changes. Your infrastructure matches the configuration.

[github-actions]

Terraform Plan Summary

core-logging-production
No changes. Your infrastructure matches the configuration.

[github-actions]

Terraform Plan Summary

core-security-production
No changes. Your infrastructure matches the configuration.

[github-actions]

Terraform Plan Summary

core-network-services-production
No changes. Your infrastructure matches the configuration.

[github-actions]

Terraform Plan Summary

core-shared-services-production
Plan: 0 to add, 1 to change, 0 to destroy.

[mikereiddigital]

I've reviewed this PR. Each account has a new provider added that calls the modernisation-account-limited-read-member-access` role and this provider is used by the environment_management data call.