Draft: Adding Secure Files to CI config

What does this MR do and why?

Related to #350934 (closed), this MR is adds the ability to configure Project-level Secure File in the gitlab-ci.yml file.

This snippet would download all files to the default folder .secure_files

job:
  script: '...'
  secure_files: 
    files: true

This snippet would download all files to the custom location ios

job:
  script: '...'
  secure_files: 
    path: 'ios'
    files: true

This snippet would only download selected files to the specified location

job:
  script: '...'
  secure_files: 
    path: 'ios'
    files: 
      - 'upload-keystore.jks'
      - 'Development_com.gitlab.unfilteredMobile.mobileprovision'

This snipped would set permissions to the files download and override the download location where specified

job:
  script: '...'
  secure_files:
    location: 'android'
    files: 
      - file: 'upload-keystore.jks'
        permissions: 'execute'
      - file: 'Development_com.gitlab.unfilteredMobile.mobileprovision'
        path: 'ios'

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