Bugfix Key and Secret role_assignements for_each loop and scope

[hjstam]

Description

• Within the for_each loop the role_assignment key is faulty, only each.value.key suffices.
• The role assignment scope should be set to the (versionless) Azure resource id.

Type of Change

• Non-module change (e.g. CI/CD, documentation, etc.)
• Azure Verified Module updates:
  • Bugfix containing backwards compatible bug fixes, and I have NOT bumped the MAJOR or MINOR version in locals.version.tf.json:
    • Someone has opened a bug report issue, and I have included "Closes #{bug_report_issue_number}" in the PR description.
    • The bug was found by the module author, and no one has opened an issue to report it yet.
  • Feature update backwards compatible feature updates, and I have bumped the MINOR version in locals.version.tf.json.
  • Breaking changes and I have bumped the MAJOR version in locals.version.tf.json.
  • Update to documentation

Checklist

• I'm sure there are no other open Pull Requests for the same update/change
• My corresponding pipelines / checks run clean and green without any errors or warnings
• I did run all pre-commit checks

[matt-FFFFFF]

Thanks for this PR. Good catch