[GitHub][workflows] Add minimum GitHub token permissions

[varunsh-coder]

Description

This PR adds minimum token permissions for the GITHUB_TOKEN in GitHub Actions workflows using https://github.com/step-security/secure-workflows.
All GitHub Actions workflows have a GITHUB_TOKEN with write access to multiple scopes.
Here is an example of the permissions in one of the workflows:
https://github.com/xbmc/xbmc/runs/7999518209?check_suite_focus=true#step:1:19

After this change, the scopes will be reduced to the minimum needed for each workflow.

Signed-off-by: Varun Sharma varunsh@stepsecurity.io

Motivation and context

• This is a security best practice, so if the GITHUB_TOKEN is compromised due to a vulnerability or compromised Action, the damage will be reduced.
• GitHub recommends defining minimum GITHUB_TOKEN permissions.
  https://docs.github.com/en/actions/security-guides/automatic-token-authentication#modifying-the-permissions-for-the-github_token
• The Open Source Security Foundation (OpenSSF) Scorecards also treats not setting token permissions as a high-risk issue. This change will help increase the Scorecard score for this repository.

This project is part of the critical projects list as per OpenSSF (https://github.com/ossf/wg-securing-critical-projects), so fixing the token permissions to improve security.

How has this been tested?

While I have not tested these particular workflows, I have added minimum permissions for similar workflows in other repositories.

What is the effect on users?

No effect on users

Screenshots (if appropriate):

N/A

Types of change

• Bug fix (non-breaking change which fixes an issue)
• Clean up (non-breaking change which removes non-working, unmaintained functionality)
• Improvement (non-breaking change which improves existing functionality)
• New feature (non-breaking change which adds functionality)
• Breaking change (fix or feature that will cause existing functionality to change)
• Cosmetic change (non-breaking change that doesn't touch code)
• None of the above (please explain below)

Improvement to the workflows.

Checklist:

• My code follows the Code Guidelines of this project
• My change requires a change to the documentation, either Doxygen or wiki
• I have updated the documentation accordingly
• I have read the Contributing document
• I have added tests to cover my change
• All new and existing tests passed

[enen92]

Looks sane. Let's get it in and look for possible regressions, if any.
Thanks much for the contribution