Protobuild Removal (MonoGame#7040)

* Protobuild removal base
* Connect VS for Mac addin to CAKE script
* Eto 2.5.0 Update
* WindowsDX and DesktopGL test projects
* Fix asset path for tests
* Tools tests
* Update Tests projects
* WindowsDX test should use netcoreapp3.0
* Connect tests to CAKE and update Tools projects
* Update MonoGame.Tools.Mac.sln
* Final CAKE fixes
* Use msbuild instead of dotnet pack on all platforms
* Ensure working directory exists for test projects
* Commit of current TeamCity build settings.
* Updated build settings on TC for Cake.
* More TeamCity build script fixes.
* Ignore... trying to force TeamCity to pull the right code changes.
* Fix CAKE script calling csproj UWP instead of WindowsUniversal
* Add criteria for WindowsDX tests
* Trying to fix unit test gathering on TeamCity.
* We wart the build version with `-develop` for development builds.
* Update the TeamCity settings.
* Don't run DesktopGL tests on mac and some minnor code fixes
* Disable tools tests
* Remove CAKE bootstrap
* [README] Add build status and update source code instructions
* [README] Add discord badge and fix source code locations
* Update README.md
Co-authored-by: Tom Spilman <[email protected]>

.gitignore

@@ -71,21 +71,6 @@ monodroid*.msi
 # Output docs
 Documentation/Output/
 
-# Protobuild Generated Files
-MonoGame.Framework.Content.Pipeline/*.csproj
-MonoGame.Framework/*.csproj
-Tools/2MGFX/*.csproj
-Tools/MGCB/*.csproj
-Tools/Pipeline/*.csproj
-Tools/MonoGame.Build.Tasks/MonoGame.Build.Tasks.*.csproj
-ThirdParty/Lidgren.Network/*.csproj
-Test/*.csproj
-!Test/MonoGame.Test.XNA.csproj
-/*.sln
-*.speccache
-*.ncrunchproject
-*.ncrunchsolution
-
 #Mac Package Files
 *.pkg
 *.mpack