Feat(remove dts): Remove the the use of DTS files

[miguelafsilva5]

PR Description

DTS files were previously used to define the following variables: tests, suites, platform, nix recipe, log and echo levels. Since the latter two variables were moved to command line options. The use of an additional file just to define effectively 3 variables, was starting to become overkill. Furthermore, in order to specify different tests and suites for different guests, would require increasing the complexity of the DTS file.

As such, we opted to move the definition of which test and suite runs on which guest to the nix recipe. Both nix recipe and platform are now passed to the framework via command line. This concentrates all configurations in a single file/recipe.

The expected command to execute the framework is:
python3 test_framework.py -recipe PATH/TO/RECIPE.nix -platform SUPPORTED_PLATFORM

And an example of a guest definition in a nix recipe:

    guests = [
          (callPackage (../../bao-nix/pkgs/guest/baremetal-remote-tf.nix)
                  { 
                    inherit system-cfg;
                    inherit toolchain;
                    guest_name = "baremetal";
                    list_tests = "";
                    list_suites = "BASIC";
                    inherit log_level;            
                  }
          )
      ];