It seems you are missing all the actions (not just InvokeProcess) from Microsoft.TeamFoundation.Build.Workflow.Activities.
These files can be found in Microsoft.TeamFoundation.Build.Workflow.dll
In addition, it looks like the Team Foundation Build Activities tab is where you include what is by default the contents of the Team Foundation LabManagement Activities tab (which are members of Microsoft.TeamFoundation.Lab.Workflow.Activities).
To add this, simply right-click on the tab and check the "System.Activities Components" box:

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