Asset retargeting has some hard coded lines for the mixed reality toolkit

[chrisfromwork]

Asset retargeting does some file/assembly lookup that assumes the assembly will be named with Microsoft.MixedReality.*: https://github.com/microsoft/MSBuildForUnity/blob/9426715dab1ffc70d3c7dcbddfd8b2cb0bf3cfc1/Source/MSBuildTools.Unity/Packages/com.microsoft.msbuildforunity/Editor/ProjectGenerator/Scripts/AssetScriptReferenceRetargeter.cs#L377

To support a wider variety of projects for asset retargeting, this should be fixed to use something more generic. Given these commands are typically called from powershell scripts it may benefit from having an argument that is the file prefix/suffix