Simplified task graph configuration

Simplified task graph configuration.

``` CSharp
Graph("Clean")
.Then("Build")
.Then("Run-Unit-Tests", If(() => runTests))
.Then("Copy-Files")
.Then("Zip-Files", If(c => c.HasArgument("zipFiles")))
.Then("Create-NuGet-Package")
.Then("Publish-NuGet-Package", If(publish))
.Then("All")
```

Start by reviewing the issue's proposed CSharp task-graph example and then locate the existing task graph configuration entry points in the repository. The issue does not name files, tests, or a concrete acceptance criterion, so the desired implementation scope and definition of done need clarification before work begins.

Written by the indexing model from the issue text.