Add helper to do bulk extraction/analysis of SkRP stages

Bug: 504647815
Change-Id: I68ba6be755e9cc42fd9f1bf69adb494c5079dff7
Reviewed-on: https://skia-review.googlesource.com/c/skia/+/1232136
Commit-Queue: Kaylee Lubick <kjlubick@google.com>
Reviewed-by: Florin Malita <fmalita@google.com>
Auto-Submit: Kaylee Lubick <kjlubick@google.com>
Commit-Queue: Florin Malita <fmalita@google.com>