Move internal code-coverage tool to use qa-tools public repo

- CI scripts to use qa-tools repository rather
than test-definitions.
- Consolidate functions to access qa-tools in a
file (qa-code-coverage.sh).
- Refactoring in merge reports script.

Signed-off-by: Saul Romero <saul.romero@arm.com>
Change-Id: I1b447273b216d739bcfcfeddf469a8f4f1c2b16b
7 files changed