Add publish functionality, refactor uploading function to utils, update Steamworks.NET

[theace0296]

I had to compile Steamworks.NET locally to implement a bug fix, hence the update to that. Refactoring the upload call to the utilities file allows the app to be expanded to do multiple files in the future (I do this on a local version).

It took a bit of tinkering plus the bug fix to Steamwork.Net to get publishing working smoothly. But I use this for my nightly publishes and it's been rock solid.

I use a style/code linter, that enforces explicit types, so let me know if you want me to switch it back to implicit types.

[veteran29]

Thank you for your contribution, I will try to find time to review it.

I would like you to use the same code style as the rest of the project, if it's changed here it would need to be changed everywhere as I do not want different code styles in the files.

Is the bugfix merged in the Steamworks.NET, could you link the changes? I would like to compile it myself as I do not want to update the DLLs from the source I do not know (sorry!).

[theace0296]

I've changed all the explicit types to implicit (where possible). If you want to see the PR for the Steamworks.NET changes, they are here: rlabrecque/Steamworks.NET#440

[theace0296]

@veteran29 This version of Steamworks.NET is the source from v14 with the changes I merged into v15 with rlabrecque/Steamworks.NET#440.