Decoding traces produced by generational aware analysis.

[cshung]

Here are the changes required to decode the traces produced by generational aware analysis I introduced in dotnet/runtime#40332

Notice the latest change requires dotnet/runtime#41052

[brianrob]

@cshung, I realize this is WIP, but wanted to give a quick bit of feedback. Overall, looks good, but I did notice that there is some addition of code to handle Gen4. I don't believe any work has been done in PerfView thus far to handle the pinned object heap, so I wanted to make sure that this is coordinated with any other work that might be done by your team on the pinned object heap.

[cshung]

@cshung, I realize this is WIP, but wanted to give a quick bit of feedback. Overall, looks good, but I did notice that there is some addition of code to handle Gen4. I don't believe any work has been done in PerfView thus far to handle the pinned object heap, so I wanted to make sure that this is coordinated with any other work that might be done by your team on the pinned object heap.

I am adding gen 4 support just to avoid asserting when trying to decode the generation bounds event. I didn't test it for anything else, it might well be broken.

[cshung]

Hi @brianrob, can I get this reviewed and merged, please?