[FEATURE] Add Newgrounds API to the project

[japtar10101]

Is your feature request related to a problem? Please describe.

Analytics, Social

Describe the solution you'd like

Use Unity's own leaderboard/achievement interface API and Newgrounds to create the super API!

Look into: https://github.com/AdamRVierra/NewgroundsAPIUnity

Tasklist

• Consider whether to move this into its own package.

Describe alternatives you've considered

https://github.com/AdamRVierra/NewgroundsAPIUnity

Additional context

Carry-over from the old Bitbucket Mercurial project:
https://bitbucket.org/OmiyaGames/hg-template-unity-project/issues/29/add-newgrounds-api-to-the-project