* Add SLN file and make projects build in VS
- Added new ActionsRunner.sln file with all the CSPROJ's in it
- Added Directory.Build.props that gets auto-included in all CSPROJ files under it
- Made default runtime platforms for Windows and Linux (to be 64bit) so that you don't have to specify it in order to build
* Remove extra invalid parens
* Remove controlling echoing by command
* Add 'echo on' and 'echo off' action commands
* PR feedback and add L0 tests
* Register new command
* Eric's PR feedback
* Tweak logging a bit
* Rename EchoOnActionCommandSuccess -> EchoOnActionCommand
* More PR reaction
* Make warning messages in Action Commands not rely on context from echo commands