Verification setup

[alfiodm]

• Setup initial CI flow
• Find a way to compile/execute bare-metal tests from dependencies
• Add more advanced regression test strategy to CI
• Execute regression on the simulation target
• Execute regression on the FPGA (demonstrator setup)

Minor (to be re-assigned to other sections?)

• Fix license headers and SV, C codestyle (currently failing CI)
• buildroot module, cloned by the cva6-sdk (in turn, used by the Cheshire dependency), sometimes cannot be cloned and causes the CI to randomly fail; possibly remove the dependency to the cva6-sdk from our custom branch of Cheshire