[roll third_party/pigweed] pw_perf_test: Reogranize source files

This CL moves `internal::Framework`, `internal::TestInfo`, and `State`
out of pw_perf_test.h and into their own separate files.

It also moves performance_test_generic.cc to
examples/example_perf_test.cc.

Finally, it removes perf_test_test.cc as this file created a no-op unit
test.

Original-Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/178914

https://pigweed.googlesource.com/pigweed/pigweed
third_party/pigweed Rolled-Commits: 998bcf980e9d1e2..e596056be5c19aa
Roller-URL: https://ci.chromium.org/b/8764774161609881121
GitWatcher: ignore
CQ-Do-Not-Cancel-Tryjobs: true
Change-Id: I91b8063219278e283feca6063fa2cd02cab3d4b6
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/experimental/+/180550
Commit-Queue: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
Bot-Commit: Pigweed Roller <pigweed-roller@pigweed-service-accounts.iam.gserviceaccount.com>
diff --git a/third_party/pigweed b/third_party/pigweed
index 998bcf9..e596056 160000
--- a/third_party/pigweed
+++ b/third_party/pigweed
@@ -1 +1 @@
-Subproject commit 998bcf980e9d1e2cc3e3ca298620c86a3fb3271c
+Subproject commit e596056be5c19aaed103d20669f54c3801dc840f