Move test_server, test data generation from third_party/boringssl back
to pw_tls_client to avoid awkward dependencies.
Change-Id: I10a885affad4b7283783da6129a2bef729037a07
Reviewed-on: https://pigweed-review.googlesource.com/c/pigweed/pigweed/+/54240
Commit-Queue: Yecheng Zhao <zyecheng@google.com>
Reviewed-by: Ali Zhang <alizhang@google.com>
