Add GitHub Actions linting workflow and Dockerfile

[KevinMind]

Fixes: #15744

Description

Add actionlint and zizmor to do static analysis on our github actions defined in mozilla/addons

Context

GIthub action pins

• docker/login-action@74a5d14
• google-github-actions/auth@140bb51
• slackapi/slack-github-action@91efab1

Testing

Checklist

• Add #ISSUENUM at the top of your PR to an existing open issue in the mozilla/addons repository.
• Successfully verified the change locally.
• The change is covered by automated tests, or otherwise indicated why doing so is unnecessary/impossible.
• Add before and after screenshots (Only for changes that impact the UI).
• Add or update relevant docs reflecting the changes made.

┆Issue is synchronized with this Jira Task

[Copilot]

Pull Request Overview

This PR adds static analysis tools for GitHub Actions workflows by introducing actionlint and zizmor linting capabilities, along with security improvements to existing workflows through action pinning and permission hardening.

• Adds Docker-based linting tools (actionlint and zizmor) with configuration files and Makefile targets
• Pins GitHub Actions to specific commit hashes for enhanced security
• Hardens workflow permissions by adding explicit permission declarations and disabling credential persistence

Reviewed Changes

Copilot reviewed 14 out of 14 changed files in this pull request and generated 3 comments.

Show a summary per file

File	Description
zizmor.yml	Configuration file for zizmor static analysis tool
docker-compose.tools.yml	Docker compose configuration for actionlint and zizmor tools
Makefile	Build targets for running linting tools
.github/workflows/transfer-issues.yml	Removes entire workflow file
.github/workflows/stale.yml	Adds empty permissions declaration
.github/workflows/docs.yml	Hardens permissions and disables credential persistence
.github/workflows/ci.yml	Adds action linting job and hardens security across all jobs
.github/dependabot.yml	Changes update interval from weekly to daily
.github/actions/slack/action.yml	Pins slack action to specific commit hash
.github/actions/slack-workflow-notification/action.yml	Adds zizmor ignore comment for unpinned action usage
.github/actions/pr-comment/action.yml	Refactors to use environment variables instead of direct substitution
.github/actions/login-gar/action.yml	Pins auth and login actions to commit hashes
.github/actions/login-docker/action.yml	Pins login action to commit hash
.github/actions/context/action.yml	Refactors to use environment variables and improves shell safety

[diox]

I had assigned the issue to me yesterday afternoon since nobody had it and was about to submit a very similar fix 😅