tools/product: integrate YAML file parsing import

This patch adds `from_yaml` class methods to `Parameter`
and `Product` classes, enabling parsing and setup of product
configurations from YAML files.
It also updates `requirements.txt` to include pyyaml module,
required for YAML processing.

Signed-off-by: Leandro Belli <leandro.belli@arm.com>
Change-Id: Iae48e46ac9b2d2e5e8cb34872caa8492aeca469e