Composite Actions: Support Env Flow (#557)

* Composite Action Run Steps

* Env Flow => Able to get env variables and overwrite current env variables => but it doesn't 'stick'

* clean up

* Clean up trace messages + add Trace debug in ActionManager

* Add debugging message

* Optimize runtime of code

* Change String to string

* Add comma to Composite

* Change JobSteps to a List, Change Register Step function name

* Add TODO, remove unn. content

* Remove unnecessary code

* Fix unit tests

* Fix env format

* Remove comment

* Remove TODO message for context

* Add verbose trace logs which are only viewable by devs

* Sort usings in Composite Action Handler

* Change 0 to location

* Update context variables in composite action yaml

* Add helpful error message for null steps

* Fix Workflow Step Env overiding Parent Env

* Remove env in composite action scope

* Clean up

* Revert back

* revert back

* add back envToken

* Remove unnecessary code

* Figure out how to handle set-env edge cases

* formatting

* fix unit tests

* Fix windows unit test syntax error

src/Sdk/DTPipelines/Pipelines/ObjectTemplating/PipelineTemplateEvaluator.cs

@@ -160,8 +160,7 @@ namespace GitHub.DistributedTask.Pipelines.ObjectTemplating
         }
 
         public List<ActionStep> LoadCompositeSteps(
-            TemplateToken token
-        )
+            TemplateToken token)
         {
             var result = default(List<ActionStep>);
             if (token != null && token.Type != TokenType.Null)