Allow github context in configValidator and overrideValidator

[sshrestha02]

• Added new property (github) in MergeDeep Constructor
• Added github context as argument whenever isValid and canOverride functions are invoked
• Added 'githubContext' as a new parameter whenever a new function is created

We also tested our changes to see if githubContext was available to use via deployment-settings.yaml :

restrictedRepos:
  # You can exclude certain repos from safe-settings processing
  #  If no file is specified, then the following repositories - 'admin', '.github', 'safe-settings' are exempted by default
  exclude: ['^admin$', '^\.github$', '^safe-settings$', '.*-test']
  # # Alternatively you can only include certain repos
  # include: ['^test$']
configvalidators:
  - plugin: repository
    error: |
      `Repository plugin errored`
    script: |
      githubContext.request('/repos/{owner}/{repo}', { owner: 'cdot-dev' , repo: 'dauxs-cdot-demo' }).then(res => { console.log(res.data) })

      if (new RegExp(baseconfig.validator.pattern).test(baseconfig.name)){
        console.log(`${baseconfig.name} matches ${baseconfig.validator.pattern}`)
      }
      return true

and we were able to successfully get a response back.

Edit: Fixed mergeDeep.test.js (mock function returns an anonymous function)