ci: Rework workflows to decrease duplication and improve maintainability.

[jamesiarmes]

No description provided.

[Copilot]

Pull Request Overview

This PR refactors GitHub Actions workflows to reduce duplication and improve maintainability by consolidating common functionality into reusable actions and separate workflow files.

• Consolidates security tooling (TFLint and Trivy) into separate dedicated workflows that can run on both push and pull request events
• Extracts common module discovery logic into a reusable composite action
• Creates a reusable action for checking GitHub security features to conditionally enable SARIF uploads

Reviewed Changes

Copilot reviewed 7 out of 7 changed files in this pull request and generated 1 comment.

Show a summary per file

File	Description
.github/workflows/trivy.yaml	New dedicated workflow for Trivy security scanning with conditional SARIF upload
.github/workflows/tflint.yaml	New dedicated workflow for TFLint checks with conditional SARIF upload
.github/workflows/pull-request.yaml	Simplified to use new changed-modules action instead of inline logic
.github/workflows/main.yaml	Removed - functionality moved to dedicated tool workflows
.github/workflows/branch.yaml	Removed - functionality consolidated into other workflows
.github/actions/security-features/action.yaml	New composite action to check repository security capabilities
.github/actions/changed-modules/action.yaml	New composite action to discover changed OpenTofu modules

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