Include TFM in the pre-built report

The pre-built report that gets generated as part of the repo source-build would benefit from mentioning the TFM that brings the pre-built in. AFAIK there's a file that mentions the projects that bring the packages in and exactly in there the TFM would be extremely useful to mention.

The scenario here are repos that build both the previous and the current TFM in the repo source-build leg. Those need to understand whether pre-builts only affect the repo-source build or the product build. By mentioning the TFM in the report, that validation would become way easier.

The information is already available in the input source for generating the prebuilt reports, the project.assets.json files.