[autotest] platform_BootPerfServer uploads perf data to new perf dashboard

Read the perf data from keyval file. Call output_perf_value()
to upload the perf data to chromeos perf dashboard.

Uploading is controlled by a tag 'upload_perf' passed from control file.
Only control.perfalearts will be uploading perf data.

Also make client/common_lib/base_utils:read_keyval
respect type_tag in the key noted in '{}', e.g. 'seconds_reboot_time{perf}'.

BUG=chromium:280634;chromium:314167
TEST=Ran the test locally, confirmed that the file "perf_measurements"
with correct perf data was outputted to the result dir.
run_suite works with dummy suite.

Change-Id: Iaf17872467dedb72878c43e563caa28cdadc9b5d
Reviewed-on: https://chromium-review.googlesource.com/175507
Tested-by: Fang Deng <fdeng@chromium.org>
Reviewed-by: Richard Barnette <jrbarnette@chromium.org>
Commit-Queue: Fang Deng <fdeng@chromium.org>
5 files changed