ci: Increase build flexibility in CI

Introduces new parameter to the check_build.py script: --products (-p) to specify individual platforms

Adds unique directories for each build done in the CI. Currently builds overwrite each other. Now, each build is given it's own build directory which is a concatenation of it's properties which is: output_path/product-group/platform/toolchain/mode/variant

Adds a configuration attribute to builds. Currently, builds within check_build can only build with default flags but this can lead to a build up of uncaught errors. Now, builds can have a specified configuration of flags

Signed-off-by: Haaris Farooq haaris.farooq@arm.com