tf-ci-gateway: produce a report table at tf-ci-gateway job

As in the Arm CI tf-ci-gateway counterpart, this commit generates a
report table summarizing all build jobs triggered. Report tables
triggered by a tf-gerrit-tforg-l1 and tf-main staging jobs can be
explored at [1,2].

One important change in the CI flow is that CI no longer needs the
'tf-a-parameterized-builder' job, so current CI flow becomes shorter:

  L level --> tf-ci-gateway --> tf-a-builder

instead of

  L level --> tf-ci-gateway --> tf-a-parameterized-builder --> tf-a-builder

[1] https://ci.staging.trustedfirmware.org/job/lsandov1-tf-gerrit-tforg-l1/42/
[2] https://ci.staging.trustedfirmware.org/job/lsandov1-tf-main/14/

Signed-off-by: Leonardo Sandoval <leonardo.sandoval@linaro.org>
Change-Id: I884a0192186d9c2d8c078c45b00bf506cdfe6566
5 files changed