(SIMP-9126) Add GHA workflows to pupmod-simp-postfix

[op-ct]

This patch adds standardized GitHub Actions to provide GitHub-based CI/CD workflows. Among this first batch are:

• PR Tests - Puppet module checks & test matrix
• PR GLCI - Auto-trigger corresponding GLCI (if actor has write perms)
• Manual: PR GLCI - Team members can trigger corresponding GLCI for a PR
• PR GLCI Cleanup - Clean up any auto-triggered GLCI pipelines/branches
• Manual: Validate API tokens - Team members can validate GHA secrets
• Tag: Release to GitHub & PuppetForge - (only on SemVer tag)

This patch also enforces the standardized asset baseline using simp/puppetsync, and may apply other updates to ensure conformity.

CI: SKIP MATRIX SIMP-9197 #close SIMP-9126 #comment Standardized GHA + assets in pupmod-simp-postfix SIMP-9149 #comment Ensured Gemfile pathspec fix for pupmod-simp-postfix SIMP-9150 #comment Remove .travis.yml from pupmod-simp-postfix