* Upgrade MSBuild references to 15.1.0-preview-000370-00
* Custom logger for MSBuild to receive telemetry events
Had to make the telemetry session ID a static variable so that the forwarding app could use it.
I've tested this all manually and will be writing tests after everyone signs off on the implementation here.
* Add support for sdk props/targets defaults to Migration.
* fix the transform applicator
* remove transform applicator dependency on insertion order for item merges
* defaults constructor msbuild version change
