platform-graphics: Refactor Harvest trace/archive code This is in preparation for generating protobufs for result DB. Refactoring the code that extracts trace data from archives into its own class. Aside from general clean up, that also makes it easier to retain trace-related data such as trace info and game info for subsequent access. BUG=None TEST=(1) Build with make and ebuild/emerge-nami. (2) Run a sample trace through Harvest on both crostini/crouton. Change-Id: I2be01af28b70d9c2ed4fa85ee512ae67273c4e34 Reviewed-on: https://chromium-review.googlesource.com/c/chromiumos/platform/graphics/+/2199756 Commit-Queue: Georges Winkenbach <[email protected]> Tested-by: Georges Winkenbach <[email protected]> Reviewed-by: David Riley <[email protected]>