[Tests] Redo the device tests

[stephen-hawley]

The device tests were done with a gross set of scripts that modified existing csproj files since there was no good way to automate them. Right now device tests are gone.
The "right" way to do this now is to:

1. build the swift pieces for the target
2. run BTfS on the generated swift library
3. make a new project with dotnet new ios
4. remove boilerplate files
5. copy in the swift libraries, the C# test files and the C# binding files
6. build with dotnet build