lava_wait_jobs.py: Produce coverage report

If coverage option is enabled:

1. Download ELF artifacts from tf-m-build-config subjob.
2. Run report preparation tools from qa-tools project:
intermediate_layer.py, generate_info_file.py, and then
lcov's genhtml.

Besides the produced report, the ELF files and qa-tools'
config/intermediate files are also included in build
artifacts, to allow reproducing and debugging results.

Implementation-wise, code coverage report related code is added to
module "codecov_helper", to separate it from the LAVA code
per se.

Signed-off-by: Paul Sokolovsky <paul.sokolovsky@linaro.org>
Change-Id: I9152674fe715e1d8b488f74cd2da2cb745010c1f
3 files changed