Nodes can now be implemented by arbitary C# methods. Graph structure is specified through expression trees implemented using Bg* types, which are not substituted with values until execution time. Doing so allows determination of node and option dependencies for a particular target, allowing us to generate dynamic UI for presenting relevant settings to the user.
Includes partial implementation of Installed Build script as an example implementation.
#preflight 61bb85d46c2686e86322eec9
[CL 18477305 by Ben Marsh in ue5-main branch]
UnrealBuild -> Unreal for EngineDirectory, RootDirectory, IsEngineInstalled, UnrealBuildToolPath
Remove CommandUtils EngineDirectory, RootDirectory, IsEngineInstalled - use equvalents from UnrealBuildBase.Unreal
#jira none
[CL 16648181 by jonathan adamczewski in ue5-main branch]