Updating MonoGame.Samples for 3.8

[SimonDarksideJ]

Starting a discussion to get a heads of agreement on a plan to update the samples to 3.8

My initial thoughts are as follows:

• [X] Review and close-out existing PR's for 3.7
• [X] Review any outstanding issues
• [X] Commit current examples to a 3.7 branch
• [X] Update develop branch samples to 3.8
• [X] Create an updated sample template using 3.8 pattern
• [X] Review new samples for 3.8

Weigh in below (before we start)

[SimonDarksideJ]

We should also incorporate feedback raised in: https://github.com/MonoGame/MonoGame/issues/7192

[harry-cpp]

I want to propose a new structure for the samples repo:

• Platformer2D
  • Platformer2D.Core
  • Platformer2D.Core.csproj - .NET Standard Library
  • Platformer2D.Linux/
  • Platformer2D.Linux.csproj
  • Platformer2D.Windows
  • Platformer2D.Windows.csproj
  • Platformer2D.Linux.sln
  • Platformer2D.Windows.sln
  • README.md
• SpaceWar
• NeoShooter
• README.md

[SimonDarksideJ]

I think it's a good idea to separate out the samples in to their own sln files. Not entirely sure about the separate lib, but I'll do some tests

[harry-cpp]

It's one of 2 standard ways for writing MG games for easy crossplatform. Another approach are shared projects, but MS has not really updated the dotnet tooling to work nicely with them, so I try to avoid them when not needed.

[SimonDarksideJ]

Samples updated to the new template @harry-cpp and working well. Even managed to make a template project which generates new projects too,

[SimonDarksideJ]

Completed, 3.7 samples archived to the 3.7 branch. Develop is now 3.8